Logical computation with canonical lifted product codes Authors Han Zheng, Guo Zheng, Liang Jiang, Qian Xu Published: 07.30.2026 Updated: 07.30.2026 Summary High-rate quantum low-density parity-check (qLDPC) codes encode many logical qubits with low physical-qubit overhead, but realizing efficient fault-tolerant computation on such dense encodings remains a major challenge. Generic, code-agnostic techniques such as code surgery and gate teleportation apply broadly, but are difficult to make modular, low-overhead, and fully certifiable on complex high-rate codes whose structure is left unexploited. Here we overcome these obstacles by co-designing the code together with its logical instruction set for a broad family of emph{canonical} lifted-product (LP) codes with cyclic symmetry. We show that these codes admit a emph{canonical logical basis}, in which conjugate logical operators are organized into rows and columns of cyclic orbits inherited directly from the underlying classical codes, analogous to the structure that makes hypergraph-product codes so tractable. This canonical basis unlocks a complete logical instruction set, including constant-depth automorphism and fold-transversal Clifford gates, modular graph code surgeries built from a constant number of reusable seed surgery gadgets or a compact canonical extractor, highly parallel logical Pauli-product measurements, and parallel magic-state injection. For example, a $[[1122,148,leq!20]]$ (resp. $[[4350,1224,leq!20]]$) LP code requires only two (resp. four) seed surgery gadgets, while arbitrary high-weight logical measurements can be implemented using a full extractor smaller than half of the data code block. These results advance the frontier of fault-tolerant quantum computation on ultra-high-rate quantum architectures. Source arXiv: 2607.28605v1
Efficient learning of bosonic unitaries beyond the Gaussian class Authors Xiaobin Zhao, Quntao Zhuang Published: 07.30.2026 Updated: 07.30.2026 Summary Multimode quantum processes are generally difficult to learn, due to the large dimensionality and complex entanglement structure beyond the Gaussian class. Here, we show that the fundamental obstruction is not non-Gaussianity itself, but the buildup of irreducible multimode non-Gaussian correlations. We establish a tractability frontier for bosonic unitary learning: a general $m$-mode unitary with input energy at most $E$ per mode requires at least $Ω(E^{2m})$ channel uses, whereas two broad non-Gaussian families—$t$-doped Gaussian unitaries and Gaussian-entanglable unitaries—can be learned with resources polynomial in $m$. The latter can exhibit both extensive non-Gaussianity and strong multimode entanglement. Our forward-only protocols use coherent-state probes, Gaussian operations, local heterodyne detection, and classical post-processing to identify the global Gaussian mixing and reduce the remaining task to single- or few-mode learning. The analysis also yields a multimode quantum Darmois–Skitovich theorem showing that mode-spreading passive networks preserve product structure only for Gaussian input states, an almost-sure activation theorem for non-Gaussian processes showing that non-Gaussian unitaries yield non-Gaussian outputs for almost all coherent input states, and a method for learning unitaries from uncalibrated coherent probes. Our results identify that complexity of learning arises from irreducible mixing of non-Gaussianity and entanglement, rather than either resource alone. Source arXiv: 2607.27534v1
From Pixels to PCells: A Neurosymbolic Approach to Photonic Component Creation Authors Aadarsh Agarwal, Kenaish Al Qubaisi, Dirk Englund Published: 07.29.2026 Updated: 07.29.2026 Summary We present PixCell, a neurosymbolic system in which multimodal agents convert a visually presented photonic component into a parametric program over a small domain-specific language (DSL) of geometric primitives. A system enabling deterministic visual verification renders evaluation asymmetrically cheaper than the generation attempt. While models using multi-seed sampling and iterative revision reach a mean best-turn IoU of only 0.416, multimodal agents through PixCell’s interface and verifier consistently exceed 0.9 mean IoU, with scores reaching 0.974 and 0.955 across eight component targets while also satisfying source contracts. These results demonstrate that frontier multimodal agents can reliably understand and render executable parametric representations from visual targets. Using these live parameters, cross-stack studies on an interferometer reconstruct primitive programs that satisfy an 8.0 nm free spectral range target and the original footprint constraint on modeled 220-nm SOI, 400-nm SiN, and 400-nm TFLN stacks. PixCell further carries a paper-derived splitter from visual reconstruction through SOI full-wave simulation, producing symmetric propagation and balanced outputs. Finally, the same executable verifier supplies a training reward and dataset used to train a Qwen3.6-35B-A3B model with LoRA and GRPO without supervised demonstrations. On eight training-excluded paper figures, its mean champion IoU rises from 0.422 after eight initial attempts to 0.491 after three verifier-guided revision rounds. These results therefore establish a controlled framework for measuring, retargeting, and improving visual-to-parametric photonic component design. Source arXiv: 2608.00084v1
Micro-electromechanical photonic integrated memristors Authors Matthew Zimmermann, Julia M. Boyle, Hardit Singh, Alex Witte, Kevin Palm, Thuy-Linh Le, Andrew J. Leenheer, Daniel Dominguez, Matt Eichenfield, Mark Dong Published: 07.23.2026 Updated: 07.23.2026 Summary Programmable optical memristors embedded in photonic integrated circuits (PICs) are emerging as an important technology for high-speed optical storage and in-memory optical computing applications. These devices provide multi-level, non-volatile storage of optical phases that can be interrogated at the speed of light, enabling parallel data readout or energy-efficient multiply-accumulate operations in artificial neural networks. However, there remains several outstanding challenges with existing optical memristor technology including durability, material-induced optical losses, large-scale reconfigurability, or fabrication yield for realistic applications. Here we introduce an analog-programmable photonic memristor based on photonic integrated micro-electromechanical (MEMS) cantilevers produced in a CMOS foundry. The memristor consists of low-loss silicon nitride waveguides, requires no additional back-end materials integration, and is all electrically programmed with electrostatic-piezoelectric forces. We demonstrate up to 5-bit phase storage levels, 50 kbit/s programming speeds, strain-assisted non-volatility lifetimes >1 hour, >1 billion cycle endurance, and stress-tested millions of write-read cycles with pseudorandom bit sequences. We further extend the memory lifetime to several days with simple electronic refresh circuits in a portable battery-powered module, demonstrating a proof-of-concept optical random-access memory in static or dynamic configurations. Our MEMS-photonics technology represents an important step toward practical optical memristors. Source arXiv: 2607.21693v1
Enhancing Entanglement Purification with Shared Randomness Authors Allen Zang, Bikun Li, Xinan Chen, Eric Chitambar, Liang Jiang, Martin Suchara, Tian Zhong Published: 07.23.2026 Updated: 07.23.2026 Summary Entanglement purification protocols (EPPs) are essential for improving entanglement fidelity to support fault-tolerant distributed quantum information processing. Practical entanglement sources are often heterogeneous and source labels may be unavailable at the EPP layer. We show that classical shared randomness, together with buffer memories, can enhance entanglement purification when source labels are unavailable, without state characterization or EPP circuit optimization. The strategy is to accumulate multiple entanglement distribution rounds and then use shared randomness to shuffle all the stored entangled states before packaging them as inputs to the EPP. For any $n$ Werner sources and any fixed $n$-to-1 bilocal Clifford EPP, we prove that accumulating and shuffling improves the expected success probability and the success-weighted output Bell fidelity over the baseline without accumulating and shuffling, for every $n$, for every finite number of accumulation rounds and in the asymptotic limit, and the improvement increases monotonically with the number of accumulation rounds. Source arXiv: 2607.21555v1
Strategic Plan for Neutral Atom Quantum Computation Authors Adrian J. Menssen, Tout Wang, Michael Gullans, Tom Manovitz, Jacob M. Taylor, Jason Cong, Josiah Sinclair, Ziv Aqua, Daniel J. Blumenthal, J. Pablo Bonilla Ataides, Johannes Borregaard, Antoine Browaeys, Paola Cappellaro, Soonwon Choi, Alexandre Cooper, Robin Côté, Jacob P. Covey, Alexandre Dauphin, Ivana Dimitrova, Matt Eichenfield, Dirk Englund, Jacob Freedman, Akihisa Goban, Brandon Grinkemeyer, Andi Gu, Ruonan Han, Dominik Hangleiter, Aram W. Harrow, Liang Jiang, Eun-ah Kim, Felix W. Knollmann, Aleksander Kubica, Thierry Lahaye, Lucas Lassabliere, Joonho Lee, Bingzhao Li, Mo Li, Wan-Hsuan Lin, Mikhail D. Lukin, Varun Menon, Thomas Propson, Akbar Safari, Mark Saffman, Pascal Scholl, Alexander Schuckert, Giulia Semeghini, Jonathan Simon, David Spierings, Daniel Bochen Tan, Shai Tsesses, Vladan Vuletic, Hanrui Wang, Hanyu Wang, Susanne Yelin, Johannes Zeiher, Hengyun Zhou Published: 07.23.2026 Updated: 07.23.2026 Summary We present a strategic plan for neutral atom quantum computation, bringing together hardware development and theory advancements to achieve the goal of practical quantum advantage. The concept of practical quantum advantage is defined, along with how to verify claims of advantage, and approaches to designing quantum algorithms that deliver practical advantage. Future directions for neutral atom quantum processor hardware are described: scaling-up system size, Qubit encodings and atomic platforms, going further below threshold with neutral-atom logical-qubit performance, continuous reloading of qubits, and fast readout. We also explore opportunities for scalable integrated photonic control technologies. Alongside hardware advancements, new developments in quantum error correction and compilation of quantum circuits are proposed. Finally, we examine the opportunity of networking multiple neutral atom quantum processors together to perform distributed quantum computing and overcome possible limitations of a single system. Source arXiv: 2607.21554v1
Sonic Stage: Automatically Generating Interactive Spatial Soundscapes to Facilitate Dialogue Video Comprehension for Blind Viewers Authors Shuchang Xu, Xiaofu Jin, Gaurav Jain, Wenshuo Zhang, Huamin Qu, Brian A. Smith, Yukang Yan Published: 07.23.2026 Updated: 07.23.2026 Summary Audio description (AD) makes film and television accessible to blind and low-vision (BLV) audiences by narrating characters’ actions. However, in scenes with lots of dialogue, AD often omits important actions because it is constrained not to overlap with speech. It is not yet known how to convey characters’ actions during dialogue. We present Sonic Stage, a system that transforms dialogue videos into interactive spatial soundscapes, enabling BLV audiences to intuitively understand characters’ actions and movements through immersive auditory cues. Sonic Stage conveys essential visual information during dialogue through three auditory techniques: (1) spatialized dialogue to represent spatial layout, (2) diegetic sound to convey character actions, and (3) interactive descriptions to provide context-specific visual details. Evaluation with 12 BLV viewers showed that Sonic Stage significantly improved video comprehension, spatial presence, and narrative engagement. We highlight opportunities for enhancing video accessibility across diverse genres through immersive, interactive audio representations. Source arXiv: 2607.20835v1
Sonic Stage: Auto-Generating Interactive Spatial Soundscapes to Facilitate Dialogue Video Comprehension for Blind Viewers Authors Shuchang Xu, Xiaofu Jin, Gaurav Jain, Wenshuo Zhang, Huamin Qu, Brian A. Smith, Yukang Yan Published: 07.23.2026 Updated: 07.30.2026 Summary Audio description (AD) makes film and television accessible to blind and low-vision (BLV) audiences by narrating characters’ actions. However, in scenes with lots of dialogue, AD often omits important actions because it is constrained not to overlap with speech. It is not yet known how to convey characters’ actions during dialogue. We present Sonic Stage, a system that transforms dialogue videos into interactive spatial soundscapes, enabling BLV audiences to intuitively understand characters’ actions and movements through immersive auditory cues. Sonic Stage conveys essential visual information during dialogue through three auditory techniques: (1) spatialized dialogue to represent spatial layout, (2) diegetic sound to convey character actions, and (3) interactive descriptions to provide context-specific visual details. Evaluation with 12 BLV viewers showed that Sonic Stage significantly improved video comprehension, spatial presence, and narrative engagement. We highlight opportunities for enhancing video accessibility across diverse genres through immersive, interactive audio representations. Source arXiv: 2607.20835v2
Dark matter searches with a 13 meV threshold superconducting sensor array Authors Christopher Albert, Lanqing Yuan, Jacob Harris, Ritoban Basu Thakur, Andrew Bear, Karl K. Berggren, Christopher Cappiello, Christopher Curwen, Peter Day, Byeong H. Eom, Arjun Ghosh, William Ho, Nikita Klimovich, Henry G. LeDuc, Karthik Ramanathan, Alejandro Simon Published: 07.21.2026 Updated: 07.21.2026 Summary Many well-motivated dark matter models predict meV-scale energy deposits in interactions with terrestrial experiments, but this regime is challenging to probe due to a lack of mature single-quantum detectors. Here we report results from QUALIPHIDE (QUAntum LImited PHotons In the Dark Experiment), a cryogenic dark matter search using a $41$-pixel array of energy-resolving microwave kinetic inductance detectors with a $13$ meV threshold, simultaneously used to look for both conversion photons from THz wavelength hidden photon dark matter and phonons from particle-like light dark matter interactions. The experimental design, with on- and off-focus pixels for the hidden photon search, allows for a data-driven background model, giving the experiment discovery potential. A blind analysis of $22$ hours of data shows no significant excess, setting the strongest constraints on the hidden photon kinetic mixing parameter $χ$ over the mass range of $13$-$90$ meV/$c^2$, reaching $1.5times10^{-12}$ at $50$ meV/$c^2$. These data also yield among the first terrestrial limits on dark matter scattering off nuclei and electrons, down to $5$ MeV/$c^2$ and $20$ keV/$c^2$, respectively. The low threshold also enables future study of the low-energy excess limiting cryogenic detectors and, as we project, will allow for a terahertz-scale QCD axion search with a magnetic field. Source arXiv: 2607.19319v1
Dark matter searches with a 13 meV threshold superconducting sensor array Authors Christopher Albert, Lanqing Yuan, Jacob Harris, Ritoban Basu Thakur, Andrew Bear, Karl K. Berggren, Christopher Cappiello, Christopher Curwen, Peter Day, Byeong H. Eom, Arjun Ghosh, William Ho, Nikita Klimovich, Henry G. LeDuc, Karthik Ramanathan, Alejandro Simon Published: 07.21.2026 Updated: 07.23.2026 Summary Many well-motivated dark matter models predict meV-scale energy deposits in interactions with terrestrial experiments, but this regime is challenging to probe due to a lack of mature single-quantum detectors. Here we report results from QUALIPHIDE (QUAntum LImited PHotons In the Dark Experiment), a cryogenic dark matter search using a $41$-pixel array of energy-resolving microwave kinetic inductance detectors with a $13$ meV threshold, simultaneously used to look for both conversion photons from THz wavelength hidden photon dark matter and phonons from particle-like light dark matter interactions. The experimental design, with on- and off-focus pixels for the hidden photon search, allows for a data-driven background model, giving the experiment discovery potential. A blind analysis of $22$ hours of data shows no significant excess, setting the strongest constraints on the hidden photon kinetic mixing parameter $χ$ over the mass range of $13$-$90$ meV/$c^2$, reaching $1.5times10^{-12}$ at $50$ meV/$c^2$. These data also yield among the first terrestrial limits on dark matter scattering off nuclei and electrons, down to $5$ MeV/$c^2$ and $20$ keV/$c^2$, respectively. The low threshold also enables future study of the low-energy excess limiting cryogenic detectors and, as we project, will allow for a terahertz-scale QCD axion search with a magnetic field. Source arXiv: 2607.19319v2
Foundry CMOS platform for multimodal quantum materials characterization Authors Sharad Kumar Yadav, Luca Nessi, Ondrej Dyck, Jinchen Wang, Bogdan Dryzhakov, Alex Melendez, Huan Zhao, Qian Song, Doha Amer, Cole Brabec, Saleh Alqazlan, Ruonan Han, Riccardo Comin, Stephen Jesse, Dirk Englund, Jawaher Almutlaq Published: 07.20.2026 Updated: 07.20.2026 Summary Quantum materials experiments increasingly rely on microwave, electrical, thermal, optical, and structural probes, but these capabilities are typically assembled from custom hardware that limits reproducibility and scalability. Here we show that a commercial 65-nm CMOS process can be repurposed as a passive, foundry-manufacturable characterization platform by functionally partitioning its metal stack into microwave, thermal, and electrical subsystems within a 1 mm2 footprint. The integrated RF architecture enables cryogenic magnetic susceptibility measurements of Fe3GeTe2 heterostructures at 1.75 K without sample-specific fabrication. We further demonstrate NV-center optically detected magnetic resonance (ODMR) with >20% contrast at 4-9 dBm microwave power, reducing power requirements by 20-25 dB relative to conventional antenna-based approaches while maintaining sensitivities of 2-3 uT/sqrt(Hz). We additionally confirm compatibility with in-situ electron-beam imaging, showing no measurable degradation in image quality upon device operation. These results establish a scalable, foundry-manufacturable platform for multimodal quantum sensing and materials characterization. Source arXiv: 2607.18059v1
Efficient routing and spectrum allocation in arbitrary flex-grid entanglement networks Authors Zachary Goisman, Matthew L. Stevens, Maxwell Goisman, Taman Truong, Gayane Vardoyan, Don Towsley, Nicholas A. Peters, Nageswara S. V. Rao, Guoliang Xue, Joseph M. Lukens Published: 07.16.2026 Updated: 07.16.2026 Summary As practical quantum networks approach large-scale deployment, the need for efficient user-to-user frequency allocation is increasing, yet current approaches only provide partial solutions to the routing and spectrum allocation problem for an arbitrary quantum network. We address this challenge for repeater-less flex-grid quantum networks based on hyperentangled photons using an efficient three-stage pipeline combining leading tools in classical networking with recent advances in numerical optimization. First, double instantiations of Yen’s algorithm obtain low-loss route candidates between each pair of users and the entanglement sources. Second, the advanced process optimizer (APOPT) obtains frequency channel allocations that maximize distribution rates under fidelity constraints. Finally, the constraint programming solver using satisfiability methods (CP-SAT) assigns specific frequency bins to each link, ensuring that there is no contention between frequencies from different sources. We numerically demonstrate this approach on a representative ring network and a Manhattan incumbent local exchange carrier topology, realizing significant improvements over prior genetic algorithm approaches in speed, accuracy, and scalability. Overall, this pipeline provides an efficient heuristic workflow for optimizing broadband entanglement distribution, applicable to arbitrarily connected quantum networks integrated within the existing lightwave infrastructure. Source arXiv: 2607.15465v1
Saturating the Bayesian Nagaoka-Hayashi bound within numerical precision for the depolarization SU(2) rotation channel Authors Leo Bia, Christos N. Gagatsos Published: 07.16.2026 Updated: 07.16.2026 Summary The Bayesian Nagaoka–Hayashi (NH) bound is a semidefinite lower bound on the Bayes risk of multiparameter estimation, tighter than the Bayesian symmertic logarithmic derivative (SLD) Cramér–Rao bounds, and whether it can be attained is an open problem. We study the single-shot estimation of a qubit rotation, all three parameters at once, under depolarizing noise and a uniform prior, with $k$ parallel uses of the channel. Rotational covariance reduces the joint optimization of probe, measurement, and estimator, and the NH bound itself, to small semidefinite programs, solvable through $k=4$. At every number of uses and noise strength the optimized strategy reaches the NH bound within the numerical precision of the calculation, numerical evidence that the bound is attained for this channel family, while the SLD bound lies strictly below and is never attained. As the noise grows the optimal probe collapses to the tensored Bell state. Source arXiv: 2607.15398v1
Ultrafast programmable Bragg reflection in photonic integrated circuits Authors Yunxiang Song, Pawan Ratra, Danxian Liu, Jiayu Yang, Zhongshu Liu, Urban Senica, Salma Mohideen, Mingjie Zhang, Xudong Li, Donald Witt, Joshua Mornhinweg, Norman Lippok, Eric Mazur, Federico Capasso, Marko Lončar Published: 07.16.2026 Updated: 07.16.2026 Summary Distributed Bragg reflectors (DBRs) are foundational building blocks of classical and quantum photonic technologies. However, their optical responses are typically fixed upon fabrication, limiting circuit robustness, reconfigurability, and functionality in applications from high-speed communications to quantum computing. Here, we demonstrate photonic chip-based programmable DBRs at telecommunications wavelengths, which are formed by electro-optically inducing refractive index contrast between periodic ferroelectric domains in thin-film lithium niobate waveguides. We achieve voltage-controlled Bragg reflection from zero to near-unity, and gigahertz-speed reflectivity modulation. Our results bring DBRs into the ultrafast programmable regime, opening new opportunities in topological photonics, cavity quantum electrodynamics, integrated lasers, and optical interconnects. The interplay between nanoscale ferroelectric domain engineering and strong electro-optic nonlinearity establishes a new design strategy for nanophotonic devices, otherwise inaccessible in bulk media. Source arXiv: 2607.14565v1
Towards a monolithic platform for coupling superconducting circuits to low-loss microwave phonons in AlScN on 4H-SiC Authors Yuanchen Deng, William W. Roberts, Sueli Skinner-Ramos, Dalton Anderson, Katherine Hewey, Xingyu Du, Michael Miller, Brandon Smith, Hwijong Lee, Pingping Chen, Charles Thomas Harris, Roy H. Olsson, Lisa Hackett, Rupert Lewis, Matt Eichenfield Published: 07.15.2026 Updated: 07.15.2026 Summary Hybrid superconducting-phonon quantum processing is promising for cavity QED, measurement-based quantum computing, and other quantum applications. Relative to microwave photons at the same frequency, phonons can provide ultra-compact footprints, extremely low losses, and greater connectivity. Phonons can also couple strongly to superconducting circuits through the piezoelectric effect. However, this promise rests on scalable platforms that achieve these benefits without degrading superconducting circuit performance. This motivates a monolithic platform combining low phononic loss, strong electromechanical coupling, and superconducting-circuit compatibility without requiring suspended phononics. Here, we characterize a monolithic quantum acoustic platform combining aluminum superconducting circuits on exposed silicon carbide (SiC) with piezoelectric aluminum scandium nitride (AlScN) on SiC for integrated phononics. This architecture is enabled by selective removal of AlScN from selected chip regions, allowing aluminum superconducting microwave resonators to be fabricated directly on the SiC while preserving adjacent AlScN-on-SiC regions for phonon transduction. The resulting Al-on-SiC resonators exhibit a coherent lifetime of 2.9 μs, demonstrating compatibility with aluminum superconducting quantum devices. In parallel, cryogenic surface acoustic delay-line measurements on the retained AlScN-on-SiC regions show low phononic propagation loss at 4.05 GHz, corresponding to an estimated phonon lifetime of 7.6 μs. Together with a previously demonstrated electromechanical coupling coefficient of about 4.3% and a theoretical upper bound of 8%, these results establish Al-on-SiC/AlScN-on-SiC as a promising monolithic platform for integrating superconducting microwave circuits with piezoelectric phononic components for quantum acoustic networking and hybrid quantum systems. Source arXiv: 2607.14319v1
Emulation of Entanglement Distribution Networks on a Quantum Computer Authors Ashley N. Tittelbaugh, Jerry Horgan, Rohan Bali, Marco Ruffini, Daniel C. Kilper, Shelbi L. Jenkins, Boulat A. Bash Published: 07.15.2026 Updated: 07.15.2026 Summary We investigate how quantum computers can be used to emulate quantum networks and study their performance under practical impairments. In particular, we evaluate how degraded entanglement and communication latency affect teleportation-based distributed multipartite-entanglement-state construction. We model imperfect Bell-pair sources using depolarizing noise channels and classical communication delays using thermal relaxation. We implement the depolarization using Stinespring dilation, randomly applied Pauli errors, and quasi-probability decompositions, evaluating the latter two on IQM quantum hardware and all three in simulation. We then study the performance of the entanglement distribution under noise generated by the aforementioned models. Although these noise models are mathematically equivalent, we find that hardware constraints result in profound differences in the corresponding results, highlighting the importance of careful experiment design. Source arXiv: 2607.14260v1
Emulation of Entanglement Distribution Networks on a Quantum Computer Authors Ashley N. Tittelbaugh, Jerry Horgan, Rohan Bali, Marco Ruffini, Daniel C. Kilper, Shelbi L. Jenkins, Boulat A. Bash Published: 07.15.2026 Updated: 07.17.2026 Summary We investigate how quantum computers can be used to emulate quantum networks and study their performance under practical impairments. In particular, we evaluate how degraded entanglement and communication latency affect teleportation-based distributed multipartite-entanglement-state construction. We model imperfect Bell-pair sources using depolarizing noise channels and classical communication delays using thermal relaxation. We implement the depolarization using Stinespring dilation, randomly applied Pauli errors, and quasi-probability decompositions, evaluating the latter two on IQM quantum hardware and all three in simulation. We then study the performance of the entanglement distribution under noise generated by the aforementioned models. Although these noise models are mathematically equivalent, we find that hardware constraints result in profound differences in the corresponding results, highlighting the importance of careful experiment design. Source arXiv: 2607.14260v2
Square-Root Law for Covert Communication with Warden-Favorable Side Information Authors Hossein Ahmadi, Christian Deppe, Boulat A. Bash, Eduard A. Jorswieck Published: 07.15.2026 Updated: 07.15.2026 Summary Covert communication enables Alice to transmit to Bob while making the transmission difficult for Willie to detect. We study a scalar Gaussian covert-overlay model in which Alice’s low-power covert signal is superimposed on an aggregate public component generated by Alice or other trackable sources. Willie is given all physically obtainable side information, including protocol details, timing, pilots, channel estimates, and calibration information, and subtracts his best estimate of the public component before testing. Covertness is imposed on the resulting residual through a relative-entropy constraint with budget $δ$ conditioned on Willie’s side information. In the stationary case, the residual under no covert transmission has variance $σ_0^2=σ_W^2+σ_e^2$, where $σ_W^2$ is Willie’s receiver-noise variance and $σ_e^2$ is the irreducible cancellation error. Over $n$ channel uses, the maximal reliably transmissible covert payload is $R_C^starsqrt{n}(1+o(1))$ bits, where $R_C^star=frac{σ_0^2}{σ_B^2ln 2}sqrtδ$, and $σ_B^2$ is Bob’s receiver-noise variance. Thus, the square-root-law (SRL) constant is governed by the variance at Willie’s actual detector input, not by receiver noise alone. Low-power Gaussian signaling achieves this constant, and a matching converse establishes first-order optimality within the conditioned additive Gaussian innovation model. For known time-varying conditioned residual variances, we also derive the first-order allocation, which assigns more covert power to larger residual variances. The results require a Gaussian post-cancellation null residual with known conditioned variance; non-Gaussian residuals and fixed non-vanishing variance uncertainty are outside the scope of this paper. Source arXiv: 2607.14013v1
Nonequilibrium thermodynamics of the acoustoelectric quantum vacuum Authors Ryan O. Behunin, Andrew Shepherd, Francesco Intravaia, Matt Eichenfield Published: 07.14.2026 Updated: 07.14.2026 Summary The quantum vacuum can assume thermal properties as a consequence of system kinematics, highlighting the nuance of our definition of particles in quantum field theory. Here, we explore this phenomenon in acoustoelectric systems, involving the interaction of phonons and plasmons, where the charge carriers drift at a constant velocity exceeding the speed of sound. Through an open quantum systems analysis, we show that the acoustoelectric quantum vacuum acquires a thermal character with a temperature defined by the drift velocity and the phonon wavevector. Realistic parameters yield effective temperatures of several Kelvin, establishing acoustoelectric systems as a promising platform for the investigation of quantum vacuum effects. Source arXiv: 2607.12228v1
Quantum-enhanced physical-layer threat detection in metropolitan-scale fiber networks Authors Yung-Cheng Kao, Siddharth Pal, Alex Forencich, Dylan Cirimelli-Low, Chaohan Cui, Jack Postlewaite, Pao-Kang Chen, Nicola Alic, Saikat Guha, Prithwish Basu, Linran Fan Published: 07.12.2026 Updated: 07.12.2026 Summary Network security is widely recognized as a key application of quantum technology. However, its large-scale deployment is hindered by the need for tight coordination between fundamentally different quantum and classical processing steps in conventional protocols. This requirement introduces strong cross-layer interdependencies that conflict with the modular, layered architectures enabling scalability in modern communication networks. Here, we present an alternative strategy that confines all quantum interventions to the physical layer and remains transparently compatible with existing network abstractions. This is achieved by directly embedding quantum features and classical information within the same optical field using bright squeezed light. Physical-layer signals are analyzed using a cumulative sum (CUSUM) method to enable quantum-enhanced threat detection. We validate the practicality of this approach through field deployment over a metropolitan-scale fiber network and further demonstrate network-level security functionalities enabled by physical-layer quantum-enhanced thread detection. These results establish a practical, scalable framework for seamlessly integrating quantum-enhanced security into large-scale communication infrastructure. Source arXiv: 2607.10799v1
Measurement-induced overconcentration in quantum generative models Authors Runzhe Mo, Bingzhi Zhang, Quntao Zhuang Published: 07.11.2026 Updated: 07.11.2026 Summary Quantum measurement is a key resource for quantum generative learning, providing intrinsic stochasticity for generating diverse quantum samples. However, in measurement-assisted state-ensemble resampling, repeated measurements can also induce overconcentration: under a fixed measurement trajectory, distinct input states progressively converge toward similar output states, suppressing input-dependent diversity. To diagnose this effect, we introduce three complementary metrics: accuracy, generative power, and input sensitivity. For Haar-random monitored circuits, we prove that one-step models retain input sensitivity up to dimension-suppressed corrections, whereas sequential monitored circuits exhibit a depth-dependent loss of input sensitivity. Motivated by this diagnosis, we propose a truncated quantum denoising diffusion probabilistic model (QuDDPM), which restricts the temporal depth of both the forward diffusion and reverse denoising processes. Numerical benchmarks show that truncated QuDDPM preserves stronger input sensitivity while maintaining accuracy and generative power comparable to the original model. These results identify measurement-induced overconcentration as a dynamical limitation of deep monitored quantum generative models and establish temporal depth as a design parameter for balancing measurement-induced randomness with input-dependent diversity. Source arXiv: 2607.10055v1
Quantum Sensors for Chemistry and Materials Science Authors Piotr Put, Arjun Pillai, Xuan Hoang Le, Mikhail D. Lukin, Hongkun Park Published: 07.08.2026 Updated: 07.08.2026 Summary The advancement of chemistry and materials science relies on transformative analytical tools which can overcome the sensitivity, spatial resolution, and throughput limitations of conventional techniques. This review explores the application of quantum sensors – specifically optically pumped magnetometers (OPMs) and nitrogen-vacancy (NV) centers in diamond – as robust platforms for molecular and materials analysis. We contrast the extreme magnetic sensitivity of macroscopic OPM ensembles with the atomic-scale resolution and multimodal capabilities of solid-state NV centers. We highlight their deployment in zero- to ultralow-field and nanoscale NMR spectroscopy, real-time reaction monitoring, and transient radical and pH detection. Furthermore, we discuss their integration into high-throughput chemical assays and non-destructive materials diagnostics, such as operando battery monitoring. With the ongoing commercialization of these technologies and advances in quantum-enhanced sensitivities, quantum sensors are poised to routinely address complex real-world analytical challenges. Source arXiv: 2607.07848v1
Design of optomechanical transducers for sub-micron resolution ultrasound imaging Authors Lisa Hackett, Chang Ge, Alex Miera, Brandon Smith, Matt Eichenfield Published: 07.03.2026 Updated: 07.03.2026 Summary Ultrasound is a noninvasive, real-time, and therefore widely used imaging modality; yet its application in cellular and sub-cellular biology is significantly limited by rapidly increasing acoustic losses in aqueous solutions with decreasing wavelength. Here we introduce a nano-optomechanical cavity transducer platform to generate and detect ultrasound in aqueous solutions with a sub-micron acoustic wavelength. We analyze the full signal pathway through a combination of finite element method modeling and the coupled differential equations that describe the dispersive optomechanical interaction. Our findings project a signal-to-noise ratio in the thousands at ~5 GHz, limited by diffraction losses and thermal-acoustic noise. This work establishes a viable path towards optomechanical ultrasound systems capable of label-free imaging at cellular and sub-cellular length scales while also providing a broader framework for optomechanical crystal device operation in aqueous environments relevant to biochemical sensing, medical diagnostics, underwater acoustic sensing, and nanoscale imaging. Source arXiv: 2607.02936v1
Monolithic Integration of Piezo-Optomechanical Photonics and CMOS Electronics Authors Matthew Zimmermann, Aileen Zhai, Andrew J. Leenheer, Julia Boyle, Mayank Mishra, Daniel Dominguez, Matthew Koppa, Wolf Jehle, Christopher Panuski, Mark Dong, Gerald Gilbert, Dirk Englund, Matt Eichenfield Published: 07.01.2026 Updated: 07.01.2026 Summary Next-generation photonic architectures for AI, sensing, and quantum computing require thousands to millions of reprogrammable photonic devices on a chip[1]. The monolithic integration of Electronically-backed Photonic Integrated Circuits (EPICs) allows for very high density electrical interconnection and electronic drivers that can scale with photonics. Piezo-optomechanical photonic integrated circuits (POMPICs) offer low power consumption, high speed modulation, cryogenic compatibility and broadband optical transparency from ultraviolet to infrared wavelengths[2,3], but have not been demonstrated with monolithically integrated CMOS electronics. Here, we show a fully monolithic, all-CMOS fabricated platform for POMPICs co-fabricated with commercial control electronics. 200 millimeter photonic wafers are constructed directly on completed CMOS driver wafers by back-end-of-line processing, connecting integrated piezoelectric actuators under broadband silicon nitride waveguides to a high-density digital backplane comprising >2 million electrical connections per die with 6.4×6.4 micron electrode pitch. We introduce segmented POMPIC components as Photonic Digital-to-Analog converters (PDACs) that convert low-voltage digital electronic signals to multi-bit analog optical phase and amplitude modulation, and we demonstrate parallel control of optical phase shifters, Mach-Zehnder interferometers, optical routing trees, and tunable ring resonators using a standard HDMI interface to program CMOS electronics. We test multiple reticles and perform electronic and photonic characterization across the entire wafer to establish uniformity and yield, demonstrating wafer-scale integration of POMPICs on an electronic backplane and enabling dense, scalable electronic control of piezo-optomechanical circuits. Source arXiv: 2607.01514v1
When AI meets quantum information: A comprehensive review Authors Min Chen, Yu Gan, Xin Jin, Yuqing Li, Junqi Wang, Zeguan Wu, Yunfei Wang, Bingzhi Zhang, Priyam Srivastava, Tianlong Chen, Ankit Kulshrestha, Yuan Liu, Juan José Mendoza-Arenas, Kaushik P. Seshadreesan, Sarvagya Upadhyay, Xueyue Zhang, Quntao Zhuang, Junyu Liu Published: 07.01.2026 Updated: 07.01.2026 Summary Artificial intelligence (AI) and quantum information (QI) are rapidly co-evolving. AI is becoming a practical tool for learning, designing, controlling, and verifying quantum systems, while QI offers new computational models, representational structures, and learning-theoretic questions for AI. This survey reviews the interface from both directions. In the AI for QI direction, we organize recent progress around the central tasks of extracting information from limited measurements, training and discovering quantum algorithms, stabilizing noisy hardware, automating experimental and programming workflows, and extending learning-based methods to sensing and networking. In the QI for AI direction, we examine how quantum computation and quantum-inspired structures affect learning through algorithmic speedups, expressivity, trainability, generalization, neural-network design, and tensor-network representations. We close by identifying cross-cutting challenges in reproducibility, scalability, hardware realism, and co-design, arguing that progress will depend on tighter integration of theory, experiment, and hybrid quantum–classical systems. Source arXiv: 2607.00365v1
PPT-Eval: A Benchmark for Computer-Use Agents on PowerPoint Tasks Authors Apurva Gandhi, Vishwas Suryanarayanan, Raja Hasnain Anwar, Firoz Shaik, Shubhang Desai, Thong Q. Nguyen, Muhammad Taqi Raza, Vishal Chowdhary, Graham Neubig Published: 06.30.2026 Updated: 06.30.2026 Summary Creating and editing slides is a rich, multimodal activity that is ubiquitous in professional and educational settings, making it an ideal testbed for real-world computer-use agents. Microsoft PowerPoint is among the most widely adopted and feature-rich environments for presentation creation. We introduce PPT-Eval, a benchmark of 120 PowerPoint tasks across 12 files that cover both content creation and presentation editing scenarios, organized by difficulty. A central challenge in this domain is evaluation: tasks are complex, multimodal, and often admit many valid solutions. Moreover, today’s agents frequently make only partial progress, which binary success metrics fail to capture. To address this, we design a robust evaluation framework to help create task-specific rubrics for PowerPoint tasks, taking inspiration from and building on past works for rubric-based evaluation. These rubrics award partial credit for intermediate steps, penalize unnecessary changes and poor aesthetics, and provide natural language feedback. This nuanced approach proves highly effective, achieving a Kendall’s τ-b correlation of 0.77 with human judgments. We find that existing frontier agents still struggle with solving PowerPoint tasks, with strong models like Claude-4.5-Opus achieving only a 45% success rate and an average partial score of 57%. The benchmark is located at: https://microsoft.github.io/ppteval. Source arXiv: 2606.31154v1
Experimental Realization of Synthetic Magnonic Lattice via Floquet Engineering Authors Amin Pishehvar, Jayakrishnan M. P. Nair, Zhaoyou Wang, Zixin Yan, Yu Jiang, Liang Jiang, Benedetta Flebus, Xufeng Zhang Published: 06.29.2026 Updated: 06.29.2026 Summary Magnonic systems, which exploit spin-wave excitations in magnetic materials, offer a promising platform for coherent information processing due to their low dissipation, strong nonlinearities, and intrinsic nonreciprocity. However, scaling magnonic circuits remains challenging, particularly with low-loss insulators such as yttrium iron garnet (YIG), which are difficult to pattern. Here, we experimentally realize a synthetic dimension in a magnonic system by coupling multimode magnon resonances in the frequency domain using time-periodic Floquet modulation. This approach enables electronically tunable interactions between discrete modes within a single YIG device, forming a reconfigurable mode-space lattice that supports functionalities such as Bloch oscillation. Our results demonstrate that high-dimensional magnonic dynamics can be achieved without increasing device footprint, establishing synthetic dimensions as a scalable and programmable route for integrated magnonic technologies. This advancement positions magnonic systems as promising platforms for engineering emergent phenomena that are inaccessible at equilibrium. Source arXiv: 2606.30845v1
A Machine-Verified Proof of a Quantum-Optimization Conjecture Authors Uri Kol, Maor Ben-Shahar, Kfir Sulimany, Dirk Englund Published: 06.29.2026 Updated: 06.29.2026 Summary We report a machine-verified resolution of a problem open for over a decade in quantum optimization: the Farhi, Goldstone and Gutmann (FGG) conjecture that depth-$p$ Quantum Approximate Optimization Algorithm (QAOA) on the ring of disagrees attains approximation ratio $(2p+1)/(2p+2)$ exactly. We found the proof using a large language model, Claude Fable 5, and verified its correctness end-to-end by the Lean 4 proof assistant. Our methodology includes several ingredients: building on a substantial Lean library of quantum information, we formalized the QAOA components and the known parts of the problem, and reduced the conjecture to a single open mathematical statement. The model was then handed the library and our agentic toolkit, and tasked with closing that gap by constructing a proof in Lean. The resulting process is a feedback loop between the model’s natural-language reasoning and Lean’s mechanical verification, which converged to a machine-verified proof. Human verification is required only for the structural scaffolding – that the formal statement faithfully encodes the intended claim – while the proof itself is supplied by the model and certified mechanically by Lean. The proof is nevertheless striking – the model uncovered a hidden dynamical symmetry of the problem and exploited it, borrowing tools and machinery from an adjacent field to turn a hard existence problem into an explicit construction. This work paves the way for resolving open conjectures in quantum information science and beyond. Source arXiv: 2606.29687v1
Exploring dynamics of individual vortices in a superconductor via a levitated magnetic transducer Authors Yiqi Wang, Trisha Madhavan, J. DaLi Schaefer, Addison NewRingeisen, Frankie Fung, Mikhail D. Lukin Published: 06.25.2026 Updated: 06.25.2026 Summary Trapped vortices determine fundamental properties of superconductors and play an important role in many practical applications such as magnetic levitation, however their complex dynamics remain poorly understood. Here, we use the mechanical motion of micron-scale levitated magnetic particles to probe the dynamics of individual vortices. Specifically, we show that the dynamics of levitated magnets are strongly influenced by vortices trapped in the YBCO superconducting film. We observe random telegraph signals in the mechanical frequency, dissipation rate, and energy of levitated particles, which we attribute to random tunneling of individual vortices. The nonlinearity of vortex-defect interaction manifests as non-exponential decay in ringdown measurements, revealing a complex underlying potential landscape. Our results provide insights into elusive dissipation mechanisms in superconducting levitated systems, open new avenues for using levitated magnets as sensitive probes of static and dynamic properties of individual vortices in superconductors and their interactions with material disorder, and point toward novel routes for using magnetic particles as highly coherent mechanical transducers. Source arXiv: 2606.27297v1
Restoring Incentive Compatibility in Two-Stage Energy Markets with Prosumers Authors Nikolas Koumpis, Koushik Kar, Leandros Tassiulas, Manolis Zampetakis Published: 06.24.2026 Updated: 06.24.2026 Summary A central challenge in modern energy market design is the formulation of a strategy-proof imbalance settlement layer that secures both the economic efficiency of the institution and the stability of the power grid. Public data reveals that the day-ahead market is strategically biased below actual consumer demand. Such empirical observations are explained by active prosumers which provide implementable incentives for demand under-reporting. Active prosumers buy energy in the day-ahead market and sell energy in the real-time market for balancing real-time energy deviations. By under-reporting their demand for the day ahead they inflate real-time imbalances and, under uniform pricing, they dispatch their generation assets more profitably. We model the two-stage institution under linear preferences and benchmark it against its associated competitive equilibria. We show that although consumers’ incentives for demand under-reporting vanish when the day-ahead market scales, prosumers’ incentives remain lower bounded by a positive gain which depends only on the real-time market generation stack and their shares over it. To restore incentive compatibility under the existing informational constraints, we design a leave-one-out contrastive scoring rule-based penalty that is implemented by the day-ahead market operator, incentivizes prosumers to report their demand truthfully and ensures small charges when participating honestly. We illustrate these results with numerical simulations on synthetic data and evaluate our mechanism on real-market data by first rationalizing demand reports as subjective equilibria of the induced game. Our mechanism demonstrates strong incentive alignment while retaining a low cost for honest participation. Source arXiv: 2606.25910v1
High-Rate and Resource-Efficient All-Photonic Quantum Repeater Architectures with 9 km Repeater Spacing Authors Ryosuke Shiina, Kenneth Goodenough, Nathan Arnold, Filip Rozpędek Published: 06.24.2026 Updated: 06.24.2026 Summary Quantum communication between two distant parties will serve as a cornerstone of the future quantum internet. However, generating enough entangled Bell pairs over long distances is a critical bottleneck. Although photons are ideal carriers of quantum information, overcoming photon loss and the exponential attenuation of signals remains a major challenge. We propose an all-photonic quantum repeater architecture that enables quantum communication over 1,000 km with an equidistant repeater spacing of 9 km. This repeater spacing is enabled by elementary entangled Bell pairs protected through the concatenation of continuous-variable and discrete-variable quantum error correction codes, namely, the bosonic Gottesman-Kitaev-Preskill (GKP) code and the [[7,1,3]] Steane code, whose combination yields a synergistic improvement in robustness against photon loss. This architecture incorporates a new ranking criterion and a multi-reflection mirror-based optical cavity as a free-space photonic memory module, which we model in terms of its length and mirror-reflection efficiency. Additionally, we propose two heuristic construction methods for the elementary entangled Bell pairs. One method introduces up to two-qubit correlated errors within each logical qubit but requires a large number of GKP qubits, while the other allows up to three-qubit correlated errors within each logical qubit but requires fewer GKP qubits. To more accurately capture realistic physical conditions during photonic resource preparation, we include switching-induced imperfections in our simulations, in addition to other standard optical imperfections. In the presence of these imperfections, our realization requires only a few thousand GKP qubits per repeater station per protocol run, a resource requirement significantly smaller than the corresponding resource requirements of prior third-generation all-photonic repeater proposals. Source arXiv: 2606.25314v1
Efficient Graph State Purification with Factorized Graph-Preserving Operations across Local Clifford Orbits Authors Mingyuan Wang, Guus Avis, Kenneth Goodenough, Stefan Krastanov Published: 06.22.2026 Updated: 06.22.2026 Summary Graph states form a broad class of multipartite entangled states underlying measurement-based quantum computation, quantum networks, and stabilizer codes. However, systematic entanglement distillation for arbitrary graph states remains challenging because the circuit design space grows rapidly with the number of parties. We introduce a group of Clifford operations that we call “factorized graph-preserving”. It enables us to efficiently enumerate and optimize graph-state purification circuits at finite size for realistic noisy hardware. These operations map products of graph-basis states to products of graph-basis states, so their action can be represented as permutations of graph-basis labels. Moreover, this useful gate set admits a compact factorized description determined by simple graph-theoretic features. This structure also allows, after some initial cached precomputation, drastically lower computational complexity for simulating a gate. We further organize these operations over local-complementation (LC) orbits using minimum-edge representatives (MERs), which let us design purification circuits that apply to all locally equivalent graph states (up to a basis change). Using this framework, we optimize noisy finite-size multipartite distillation circuits for several graph-state families. Numerical results show that the resulting graph-preserving circuits can outperform standard recurrence-based purification protocols under realistic gate and measurement noise. Our results establish LC-orbit structure and factorized graph-preserving operations as practical tools for scalable, topology-aware and hardware-constrained graph-state distillation protocol design. Our work can also be interpreted as a graph-based heuristic for finding transversal gates. Source arXiv: 2606.23809v1
Persistent structural distortions and absent superconductivity in trilayer nickelate thin films Authors Abigail Y. Jiang, Maria Bambrick-Santoyo, Lopa Bhatt, Kyeong-Yoon Baek, Yi-Feng Zhao, Dan Ferenc Segedin, Ari B. Turkiewicz, Jenna Hatmin, Grace A. Pan, Suchismita Sarker, Donald A. Walko, Charles M. Brooks, David A. Muller, Berit H. Goodge, Hua Zhou, Antia S. Botana, Julia A. Mundy Published: 06.18.2026 Updated: 06.18.2026 Summary A new family of high-temperature superconductors was recently discovered in the $n=2,3$ Ruddlesden-Popper nickelates, where superconductivity emerges concomitant with suppression of parent density waves and structural octahedral rotations under hydrostatic pressure. Intriguingly, compressive strain mimics the structural effects of pressure in the $n=2$ phase, yielding ambient-pressure superconductivity. However, analogous strain-stabilized superconductivity has not been realized in the $n=3$. Here, we use atomically-precise synthesis, transport, picoscale electron microscopy, and synchrotron X-ray diffraction to probe $n=3$ La$_4$Ni$_3$O$_{10}$ thin films. Although compressive strain suppresses density wave order, we do not observe superconductivity even under the largest strain state. Importantly, we identify a structural distortion unique to strained $n=3$ thin films that may inhibit superconductivity: persistent, layer-inequivalent octahedral rotations around the $c$-axis. Our results highlight key differences between the $n=3$ and $n=2$ systems, suggesting that ambient-pressure superconductivity in the $n=3$ may require new methods beyond epitaxial strain engineering. Source arXiv: 2606.20941v1
Impulse Decoding of Quantum LDPC Codes: Equivalence of Degeneracy and Code-Shortening Authors Shobhit Bhatnagar, Michele Pacenti, Nithin Raveendran, David Declercq, Bane Vasić Published: 06.16.2026 Updated: 06.16.2026 Summary Quantum error correction is essential for building scalable quantum computers. Within the stabilizer formalism, the Calderbank-Shor-Steane framework constructs quantum codes from pairs of classical linear codes. A distinctive feature in this setting is degeneracy, where multiple equivalent error estimates exist-a phenomenon that has no classical counterpart, and the lack of a meaningful classical coding-theoretic interpretation of which has remained a gap in the literature. In this paper, we demonstrate that degeneracy is closely related to the classical operation of shortening of a linear block code. Interestingly, the shortening here takes place at the decoder rather than at the encoder. Leveraging this insight, we present a parallel decoding scheme for quantum low-density parity-check codes, which we term impulse decoding, that significantly outperforms belief propagation with ordered statistics decoding, as well as several other existing techniques, under both code-capacity and circuit-level noise, with significantly lesser complexity. We then present another algorithm based on decoding of residual errors, which when combined with impulse decoding achieves further performance improvement under circuit-level noise. Source arXiv: 2606.18240v1
Optimal Probe State for Phase Estimation Under Covariant Measurement Authors Qipeng Qian, Christos N. Gagatsos Published: 06.16.2026 Updated: 06.16.2026 Summary We study the optimization of input states for phase estimation under covariant measurements. Building on Holevo’s framework, which provides the optimal covariant measurement for a fixed input state, we further optimize over the input state itself. For a general even $2π$-periodic cost function with non-negative Fourier coefficients, we derive a necessary and sufficient condition for the optimal input state: Its Fock coefficients are determined, up to arbitrary phases, by the eigenvector corresponding to the largest eigenvalue of a Toeplitz matrix defined by the cost function. This characterization yields an explicit expression for the attainable lower bound of the average cost under optimal covariant measurements and shows that this bound asymptotically approaches zero in the infinite-energy limit. For the specific cost function $W(θ,tildeθ)=4sin^2[(θ-tildeθ)/2]$, we obtain the optimal input state and the corresponding minimum average cost in closed form, demonstrating Heisenberg scaling with respect to the mean photon number. Source arXiv: 2606.18169v1
Probing La-based nickelates with Ni 1$s$ core-level photoelectron spectroscopy Authors Daisuke Takegami, Naoki Ito, Koto Fujinuma, Masato Yoshimura, Grace A. Pan, Dan Ferenc Segedin, Qi Song, Hanjong Paik, Charles M. Brooks, Hanjie Guo, Alexander C. Komarek, Takanori Taniguchi, Masaki Fujita, Julia A. Mundy, Takashi Mizokawa, Liu Hao Tjeng, Berit H. Goodge, Atsushi Hariki Published: 06.16.2026 Updated: 06.16.2026 Summary We present a comparative Ni core level photoemission study of La$_3$Ni$_2$O$_7$, Nd$_3$Ni$_2$O$_7$, and LaNiO$_3$ using both the Ni $2p$ and the Ni $1s$. We address the challenges in analyzing the widely investigated Ni $2p$ spectra arising from the substantial overlap in energy of the Ni $2p$ with the La $3d$. We show that on the other hand the deep Ni $1s$ core level does provide a clean view on the intrinsic electronic excitations and we highlight its potential to resolve detailed differences in the electronic structure within the strongly correlated Ruddlesden-Popper series La$_{n+1}$Ni$_n$O$_{3n+1}$. Source arXiv: 2606.17663v1
Ling and Ring 2.6 Technical Report: Efficient and Instant Agentic Intelligence at Trillion-Parameter Scale Authors Ang Li, Ben Liu, Bin Han, Bin Hu, Bin Jing, Binbin Hu, Bing Li, Cai Chen, Caizhi Tang, Changxin Tian, Chao Huang, Chao Zhang, Chen Liang, Chen Qian, Chengfu Tang, Chengyao Wen, Chilin Fu, Chunwei Wu, Cong Zhang, Cunyin Peng, Daixin Wang, Dalong Zhang, Deng Zhao, Dingnan Jin, Dingyuan Zhu, Donghao Zhang, Fan Yuan, Fangzheng Zhao, Fanzhuang Meng, Feifan Wu, Feng Xu, Fengbin Fang, Gangshan Wang, Guodong Yang, Hailin Zhao, Haitao Wang, Haitao Zhang, Hanxiao Zhang, Hanzi Wang, Hao Dai, Hao Liu, Hao Qian, Hao Wu, Haoxiong Liu, Haoyu Xu, Heng Zhang, Hong Liu, Hongliang Zhang, Hongrui Liu, Hongxun Li, Hongzhi Ruan, Huaidong Xiong, Huihuang Zheng, Huikang Tang, Jia Guo, Jia Li, Jia Liu, Jiameng Wang, Jiaming Liu, Jiannan Shi, Jianping Wei, Jiaolong Yang, Jiapeng Wang, Jie Gao, Jie Wang, Jiewei Wu, Jin Yang, Jinjin Li, Jinjing Huang, Jinquan Sun, Jinyao Chen, Juanhui Tu, Jun Liu, Jun Mei, Jun Xu, Jun Zhou, Junjie Ou, Junnan Sipan, Junpeng Fang, Kaihong Zhang, Kaiqin Hu, Ke Shi, Kuan Xu, Kun Tang, Kunlong Chen, Lanyin Mei, Lei Chen, Lei Liang, Lei Xu, Li Tang, Liang Jiang, Liangcheng Fu, Lihui Zhang, Linfeng Shi, Lintao Ma, Liyuan Liu, Longfei Li, Longfei Zheng, Lu Liu, Lu Yu, Man Li, Meiqi Zhu, Meng Li, Mengjie Gao, Mengshu Sun, Mingming Yin, Mingyang Zhang, Mingyuan Fan, Nuo Xu, Pan Tang, Peijie Jiang, Peilong Zhao, Peng Lin, Pingping Liu, Qi Zuo, Qian Zhao, Qiang Cheng, Qianggang Cao, Qiaoben Bao, Qing Cui, Qingyuan Yang, Qitao Shi, Qiyin Huang, Qizheng Zhou, Quan Wan, Runyuan Zhao, Shaomian Zheng, Shaowei Wei, Shengnan Zhang, Shuaicheng Li, Shujie Li, Shuo Zhang, Sikang Bian, Tianchu Yao, Tiange Xu, Tianshu Wang, Ting Guo, Tinghao Wang, Tingwei Huang, Tong Zhao, Tongkai Yang, Wang Hong, Wanli Gu, Wei Lu, Weichang Wu, Weiguang Han, Weiquan Li, Wenbo Shen, Wenjing Fang, Wenzhi Tang, Xiang Shu, Xiao Shi, Xiaodong Yan, Xiaolu Zhang, Xiaopei Wan, Xiaqing Sun, Xin Zhao, Xingyu Lu, Xinxing Yang, Xinyao Tang, Xinyu Kong, Xinyu Liu, Xiong Xu, Xuan Sun, Xudong Han, Xudong Wang, Xujie Shen, Yalin Zhang, Yangyang Hou, Yankun Ren, Yao Zhao, Ye Chen, Yeyang Chen, Yibo Cao, Yifan Zuo, Yijie Chen, Ying Li, Yingjie Song, Yingxue Li, Yiqi Wang, Yixuan Sun, Yizhu Xiao, Yongfei Xu, Yu Liu, Yuchen Fang, Yue Gao, Yue Yu, Yue Zhang, Yuqi Zhang, Yuxiao He, Yuxiao Lu, Yuxin Tian, Yuxuan Li, Yuzhuo Fu, Zhankai Xu, Zhaoxin Huan, Zhenduo Zhang, Zhengke Gui, Zhengyu Huang, Zhenjun Ma, Zhenxuan Pan, Zheping Qu, Zhibo Zhu, Zhidong Fan, Zhigang Huangfu, Zhihao Wang, Zhiqiang Zhang, Zhizhen Liu, Zhuyan Zhou, Zibin Lin, Zihang Zeng, Zihao Wang, Zilong Wang, Ziqi Liu, Zitao Xuan, Zixuan Cheng, Zujie Wen, Zuoli Tang Published: 06.13.2026 Updated: 06.13.2026 Summary Efficient and scalable agentic intelligence requires models that can deliver both low-latency responses and strong reasoning capabilities while remaining practical to train, serve, and deploy. In this report, we present Ling-2.6 and Ring-2.6, a family of models designed to address this challenge at scale. Ling-2.6 is optimized for instant response generation and high capability per output token, whereas Ring-2.6 is tailored for deeper reasoning and more advanced agentic workflows. Instead of training from scratch, we upgrade the Ling-2.0 base model through architectural migration pre-training and large-scale post-training. This upgrade is guided by a unified co-design of model architecture, optimization objectives, serving systems, and agent training environments, enabling improvements in both model capability and deployment efficiency. At the architectural level, we introduce a hybrid linear attention design that integrates Lightning Attention with MLA, improving the efficiency of long-context training and decoding. To further enhance token efficiency, we optimize capability per output token through Evolutionary Chain-of-Thought, Linguistic Unit Policy Optimization, bidirectional preference alignment, and shortest-correct-response distillation. For agentic capabilities, we propose KPop, a reinforcement learning framework designed to support stable training of Ring-2.6-1T on large-scale environment-grounded data. KPop improves training efficiency through asynchronous scheduling across coding, search, tool use, and workflow execution, enabling scalable learning from complex agent-environment interactions. Together, Ling-2.6 and Ring-2.6 provide a practical pathway toward efficient, scalable, and open agentic systems. We open-source all checkpoints in the 2.6 family to support further research and development in practical agentic intelligence. Source arXiv: 2606.15079v1
Fundamental Limit for One versus Two Point Sources Detection using Direct Imaging Authors Parth Hemant Darekar, Amit Kumar Jha, Michael R. Grace, Aqil Sajjad, Saikat Guha Published: 05.31.2026 Updated: 05.31.2026 Summary We consider the task of distinguishing between a single weak incoherent optical point source and two weak incoherent optical point sources located symmetrically about the first source. $θ$ is the separation between the two point sources scaled to the Point Spread Function (PSF) width in the image plane. Using an ideal focal plane array of intensity detectors (ideal direct imaging), we quantify the performance using the Bhattacharyya distance and find the scaling of its leading order term in terms of $θ$ in the sub-Rayleigh regime. A suite of previous analyses of this problem lacked a comprehensive analysis for when the amplitude spread function (ASF) of the imaging system has zeros and reported a scaling that we find to be incorrect. We complete this analysis by explicitly calculating the leading order term of the Bhattacharyya distance for ideal direct imaging with any ASF, for small $θ$ and show the difference in scaling based on the presence or absence of zeros in the ASF. This is similar to the ASF dependent performance in the task of estimating the separation between the two point sources and the task of detecting a change to an object. We then apply our results to the specific example of a Gaussian and a Sinc ASF and show good agreement with numerical calculations. Our results allow the accurate comparison of other measurement schemes with ideal direct imaging, and to the quantum limit. Source arXiv: 2606.00968v1
Learning Mid-circuit Measurement Backaction from Three Repeated Measurements Authors Chia-Tung Chu, Su-un Lee, Han Zheng, Senrui Chen, Bibek Pokharel, Alireza Seif, Liang Jiang Published: 05.29.2026 Updated: 05.29.2026 Summary Accurate modeling of mid-circuit measurements (MCMs) is essential for dynamic-circuit operations such as syndrome extraction, measurement-based reset, and the separation of state-preparation and measurement (SPAM) error. Unlike terminal measurement, a noisy MCM both produces a classical outcome and alters the incoming quantum state, thereby influencing subsequent circuit operations. This makes conventional confusion-matrix or fidelity-level characterization insufficient. Here we introduce an efficient, self-consistent protocol for learning a single-qubit Z-twirled MCM instrument, retaining the readout-backaction correlations and excitation-decay asymmetry that are erased in Pauli-error descriptions. Remarkably, readout bit strings from only three repeated MCMs on a maximally mixed input determine all learnable parameters of the reduced instrument, up to a single unidentifiable gauge degree of freedom. Physicality constraints convert this non-identifiability into narrow, gauge-aware error intervals. Implemented on IBM superconducting processors, the learned instrument improves Pauli-observable prediction by ${sim}100times$ over a conventional confusion-matrix model and reveals a $T_1$-decay dominated backaction. Our protocol provides a compact characterization layer for SPAM error separation, reset optimization, and noise-aware quantum error correction. Source arXiv: 2606.00433v1
No-Go Theorem for Ancilla-Assisted Gaussian Enhancement in Passive-Unitary Estimation Authors Zihao Gong, Saikat Guha Published: 05.29.2026 Updated: 05.29.2026 Summary We study the maximum quantum Fisher information (QFI) for estimating a single parameter embedded in a generic multimode lossless passive Gaussian unitary using general Gaussian probes under a signal-energy constraint. Unlike previous work, which imposed a total energy constraint on the full probe, we constrain only the transmitted signal modes while allowing an arbitrary number of locally retained ancilla modes with arbitrarily large energy. We prove that this additional freedom does not increase the maximum achievable QFI; the optimum remains identical to that attainable without extra ancilla energy. The same conclusion also extends to the sequential setting under a total energy constraint. We also characterize the family of optimal probe states and show that entanglement is not necessary to attain the optimum in the lossless setting. This extends the result of Matsubara et al. to the physically motivated signal-energy-constrained scenario and establishes a no-go theorem for ancilla-assisted Gaussian enhancement in noiseless passive-unitary estimation. Source arXiv: 2606.00256v1
Toward Practical Two-Way Covert Communication Authors Paul N. Fessatidis, Wyatt Wallis, Tae E. Cooper, Mark J. Meisner, Jaim Bucay, Saikat Guha, Shelbi L. Jenkins, Michael S. Bullock, Boulat A. Bash Published: 05.28.2026 Updated: 05.28.2026 Summary We study two-way covert communication schemes, where information is transmitted by passively modulating a reflected signal back to the source. We consider optical systems, described by quantum bosonic channels. While broadband classical and quantum light sources offer high covert throughput in theory, the associated mode-matching and phase-synchronization requirements make them impractical. Therefore, we employ a narrowband laser source to experimentally demonstrate a proof-of-concept two-way covert communication system, where the adversary is assumed to be quantum-capable. Furthermore, we propose a correlator-based receiver that attains the broadband gain offered by a quantum light source without the need for precise mode matching. Source arXiv: 2605.29840v1
18-dB on-chip vacuum squeezing in an adaptively poled lithium niobate waveguide Authors Tushar Sanjay Karnik, Xinyi Ren, Chun-Ho Lee, Bo-Han Wu, Mihir Chaudhari, Clayton Cheung, James Wang, Shi-Yuan Ma, Mahmoud Jalali Mehrabad, Ian Christen, Reshma Kopparapu, Kiwon Kwon, Yue Yu, Sri Krishna Vadlamani, Kamila Kunes, Quntao Zhuang, Dirk Englund, Zaijun Chen, Mengjie Yu Published: 05.26.2026 Updated: 05.26.2026 Summary Quantum squeezed states of light can enhance measurement sensitivity beyond classical limits and enable quantum information processing, but scalable low-loss sources remain challenging. We demonstrate continuous-wave quantum squeezing on a chip, achieving 18 dB of squeezing and 20 dB of anti-squeezing at 1570 nm in a 1.6-cm traveling-wave adaptively poled thin-film lithium niobate waveguide. A distributed model independently determines facet losses, phase noise, and nonlinear interaction strength without prior assumptions, enabling rigorous inference of on-chip performance. We estimate a 95% confidence interval of [-18.96, -17.25] dB squeezing and [19.96, 21.35] dB anti-squeezing. These values represent the highest squeezing reported for any integrated photonic platform and the first assumption-free statistical validation of integrated squeezing performance. Our results establish thin-film lithium niobate as a high-performance, scalable platform for continuous-variable quantum sensing, communications, and photonic computing. Source arXiv: 2605.27607v1
Dispersive readout of cavity-coupled solid-state sensor with near-unity readout fidelity Authors Hanfeng Wang, Shuang Wu, Matthew E. Trusheim, Avetik Harutyunyan, Dirk R. Englund Published: 05.24.2026 Updated: 05.24.2026 Summary Solid-state quantum sensors based on ensembles of nitrogen-vacancy (NV) centers in diamond have emerged as powerful platforms for high-precision metrology. Coupling the NV ensemble to a microwave cavity mode in a cavity quantum electrodynamics (cQED) configuration enables spin readout that surpasses the limitations of conventional optical detection, achieving sub-picotesla magnetic sensitivities. However, existing continuous-wave cQED approaches remain far from the intrinsic spin-projection-noise limit due to spin saturation and power broadening. Here, we introduce a dispersive cQED readout technique to overcome these fundamental limitations in NV ensemble sensing. We develop a comprehensive theoretical framework describing the dispersive interaction and analyze the time-domain dynamics of a strongly-coupled NV-cavity system. Our results indicate near-unity inverse readout fidelity and femtotesla-level sensitivity using a commercially available diamond NV ensemble. Importantly, the dispersive readout exhibits a distinct sensitivity scaling that improves as 1/N with increasing number of spins N, providing a practical pathway toward approaching the standard quantum limit for solid-state spin-ensemble sensors. Source arXiv: 2605.25152v1
Reasoning through Verifiable Forecast Actions: Consistency-Grounded RL for Financial LLMs Authors Jialin Chen, Aosong Feng, Harshit Verma, Siyi Gu, Haiwen Wang, Ali Maatouk, Yixuan He, Yifeng Gao, Leandros Tassiulas, Rex Ying Published: 05.21.2026 Updated: 05.21.2026 Summary Financial markets are characterized by extreme non-stationarity, low signal-to-noise ratios, and strong dependence on external information such as news, company fundamentals, and macroeconomic signals. Yet, existing approaches either abstract time-series into text or decouple forecasting from language-based reasoning, leading to a fundamental mismatch between qualitative reasoning and quantitative outcomes. To address this, we introduce StockR1, a time-series-enhanced LLM that unifies stock forecasting and financial reasoning through a verifiable forecast action. Based on a tool-call design, the model first emits a forecast action, which is a structured and interpretable representation of its qualitative market outlook. It then invokes a time-series decoder conditioned on this action to generate distributional future trajectories, leading to more informed question answering and financial reasoning. We optimize the full pipeline with reinforcement learning, where rewards jointly reflect answer validity, forecast accuracy, and consistency between generated actions and observed time-series dynamics. In addition, rewards are reweighted by a sample-level uncertainty scalar, encouraging the model to accommodate varying uncertainty in market dynamics. We evaluate StockR1 on financial question answering and stock forecasting over a large-scale 10-year benchmark. Our method consistently outperforms time-series baselines and general-purpose LLMs, improving reasoning accuracy by 17.7% (4B) and 25.9% (8B). These findings demonstrate that structuring the forecast actions establishes a powerful synergy between language reasoning and temporal prediction, enabling LLMs to reason through verifiable, interpretable, and numerically grounded decisions. Source arXiv: 2605.21975v1
Toward Covert Quantum Computing Authors Evan J. D. Anderson, Kaushik Datta, Boulat A. Bash Published: 05.14.2026 Updated: 05.14.2026 Summary As quantum computers become available through multi-tenant cloud platforms, ensuring privacy against adversaries sharing the same quantum processing unit becomes critical. We introduce and explore emph{covert quantum computing}, a new concept that ensures an adversary with access to all other quantum computational units (QCUs) of a quantum computer cannot detect computation on the subset that they cannot access. Analogous to covert communication, we employ information theory. However, since here the adversary controls the systems used for detection, we require a richer framework for covertness analysis that accounts for the use of quantum memories and adaptive operations. Thus, we adopt the emph{quantum-strategy} framework used in quantum game theory and memory channel discrimination. Current quantum computers use planar graph circuit layouts and typically assume nearest-neighbor crosstalk. We derive discrete isoperimetric inequalities to show that, for an $n$-qubit circuit under this model, only $mathcal{O}(sqrt{n})$ border qubits provide detection information to the adversary. We then explore this scaling law on IQM’s 54-qubit emph{Emerald} processor and IBM’s 156-qubit emph{ibm_fez} machine employing the Heron 2 architecture. We implement Ramsey experiments on qubits not used in computation, and detect nearest-neighbor crosstalk, as expected. However, we also observe long-range coupling effects beyond the border qubits, revealing a side channel that the adversary can exploit. We hypothesize that this long-range crosstalk is induced by leakage from the drive and control lines. Beyond weakening covertness, it exposes co-tenants to both adversarial and unintended crosstalk and degrades circuits that span spatially distributed qubits, motivating further work on spatial isolation and crosstalk characterization. Source arXiv: 2605.14325v1
Chaos Emerge with Exceptional Points in Reset-Driven Floquet Dynamics Authors Jia-jin Feng, Quntao Zhuang Published: 05.12.2026 Updated: 05.12.2026 Summary We investigate the spectral structure of reset-driven Floquet quantum channels generated by the Hamiltonian evolution of a many-body system followed by periodic resetting of a bath. By tuning a chaos-controlling parameter in the underlying Hamiltonian, we uncover an exceptional-point-induced spectral transition from a symmetry-constrained ergodic regime to a fully chaotic regime. Across this transition, increasing the chaos parameter causes the real eigenvalues of the channel to drift, coalesce at exceptional points, and bifurcate into complex-conjugate pairs, signaling the progressive breaking of symmetry constraints in operator space. We further show that the channel spectrum sharply distinguishes chaotic, ergodic, many-body localized, and scarred dynamical regimes. Finally, we connect the leading channel eigenvalues to experimentally accessible probes based on quantum mutual information, establishing a link between the spectral organization of reset-driven quantum channels and observable relaxation dynamics. Source arXiv: 2605.11751v1
Optical signatures of antiferromagnetic correlations in a strongly interacting quantum Hall MoSe2 monolayer Authors Jiho Sung, Pavel A. Volkov, Ilya Esterlis, Jue Wang, Luke N. Holtzmann, Takashi Taniguchi, Kenji Watanabe, Katayun Barmak, James Hone, Mikhail D. Lukin, Philip Kim, Hongkun Park Published: 05.11.2026 Updated: 05.11.2026 Summary Strong magnetic fields quench the kinetic energy of electrons, leading to the formation of flat energy bands, known as Landau levels (LLs). In this situation, even weak interactions can drive the emergence of various ordered phases. The simplest of such phases is a quantum Hall ferromagnet, where a spontaneous spin polarization emerges when LLs with opposite spins cross. The presence of strong electron-electron interaction at zero field changes this picture and makes the resulting states much harder to predict. Here we use magneto-optical spectroscopy to reveal quantum Hall states with unconventional correlations favouring an unpolarized state in the strongly correlated electron liquid in a MoSe2 monolayer. The oscillations of the exciton polaron energies as a function of perpendicular magnetic field and electron density demonstrate the emergence of LLs in a correlated electron liquid and density-dependent crossings between LLs of opposite valleys. On lowering the LL filling factor, where interactions within LLs are stronger, the crossings systematically broaden, indicating an increase in the Zeeman energy required to fully polarize the valley-degenerate LLs. These observations are shown to be consistent with antiferromagnetic interactions between LL electrons, favouring a ground state with zero valley polarization, and are therefore inconsistent with conventional quantum Hall ferromagnetism. This discovery demonstrates a qualitatively distinct form of quantum Hall magnetism in a strongly correlated electron liquid, establishing an anchoring point for understanding spin-unpolarized fractional and ordered states of correlated electrons driven by magnetic field. Source arXiv: 2605.11249v1
Rank Is Not Capacity: Spectral Occupancy for Latent Graph Models Authors Nikolaos Nakis, Panagiotis Promponas, Konstantinos Tsirkas, Katerina Mamali, Eftychia Makri, Leandros Tassiulas, Nicholas A. Christakis Published: 05.11.2026 Updated: 05.11.2026 Summary Graph representation learning has become a standard approach for analyzing networked data, with latent embeddings widely used for link prediction, community detection, and related tasks. Yet a basic design choice, the latent dimension, is still treated as a brittle hyperparameter, fixed before training and tuned by held-out performance. Learned factors are also identifiable only up to rotation and rescaling, so the nominal rank rarely coincides with the quantity that governs model behavior. We propose Spectral Prefix Extraction and Capacity-Targeted Representation Analysis (Spectra), which replaces rank as the unit of analysis with the spectrum of a learned positive semidefinite kernel, trace-normalized so that spectra are comparable across fits. The normalized eigenvalues form a distribution on the simplex, and their Shannon effective rank acts both as a summary of learned capacity and as a controllable training-time coordinate: a single scalar shapes this realized dimension during training, and bisection targets any desired value within the rank cap. To theoretically support that, we show local regularity and monotonicity of the realized-dimension profile. Across collaboration, social, biological, and infrastructure networks, Spectra traces performance–capacity frontiers that make the trade-off between predictive accuracy and realized dimension visible. It performs competitively with strong link-prediction baselines, yields aligned lower-capacity views of the same fitted model through spectral prefixes, and provides a principled handle on capacity in the overparameterized regime. Capacity thus becomes a property of the fitted model rather than a hyperparameter of the training. Source arXiv: 2605.11142v1
Passive optical superresolution at the quantum limit Authors A. I. Lvovsky, Michael R. Grace, Saikat Guha, Mankei Tsang, Gerardo Adesso, Nicolas Treps Published: 05.11.2026 Updated: 05.11.2026 Summary For more than a century, the diffraction limit has defined the resolution achievable by passive optical imaging systems. Although some resolution improvement can be gained through classical data processing of the image, it is limited by the noise arising from quantum nature of light. Minimizing the effect of this noise requires quantum treatment of optical imaging. By reformulating imaging as a problem of quantum measurement and estimation, it becomes possible to identify optimal detection strategies that recover spatial information previously thought inaccessible. This review summarizes the theoretical framework that underpins this development, from the formulation of quantum Cramér-Rao bounds and Chernoff bounds to the construction of receivers that attain them, such as those based on spatial-mode demultiplexing. We show how these methods can beat conventional imaging in the classification, localization, and imaging of sub-Rayleigh incoherent sources. We then discuss extensions to multiparameter and partially coherent scenarios, and highlight the unifying connections between estimation and discrimination tasks. Finally, we survey recent experimental demonstrations that approach quantum-limited resolution and outline emerging applications in microscopy, astronomy, and optical sensing. Source arXiv: 2605.10767v1
Raman suppression in nanophotonics enabled by multimode spectral filtering Authors Yunxiang Song, Jinsheng Lu, Xinrui Zhu, Danxian Liu, Zongda Li, Pawan Ratra, Norman Lippok, Miro Erkintalo, Federico Capasso, Marko Loncar Published: 05.09.2026 Updated: 05.09.2026 Summary Miniaturized photonic cavities generating nonlinear optical states of light are central to telecommunications and metrology applications. The emergence of such states is primarily underpinned by the ubiquitous Kerr nonlinearity that is present in all media. However, stimulated Raman scattering (SRS), an additional process inherent to many materials, has been shown to critically hinder the states’ formation, imposing fundamental constraints on the choice of photonic platforms. Here, we introduce a novel strategy for the suppression of SRS in nanophotonic devices, adaptable to diverse Raman spectral responses. This is achieved by controlling the coupling and loss among multiple transverse spatial modes of the system, tailored across ultrabroad spectral bandwidths. Specifically, we combine nanometrically-corrugated Bragg gratings and tapered waveguides that, together enable co-directional multimode coupling and mode-selective filtering. We use lithium niobate as an exemplary Raman-active material to realize the concept, and we demonstrate the robust generation of two distinct Kerr nonlinear states (corresponding to coherent optical frequency combs) using the fabricated devices. The simplicity and generality of the concept suggest wide applicability to classical and quantum light generation on many technologically-relevant platforms nominally plagued by SRS (e.g., silicon and diamond photonics). More broadly, our multimode spectral shaping and filtering concept opens a path forward for highly-structured, wavelength-specific losses in nanophotonic waveguides and cavities, with potential applications in ultrafast and nonlinear integrated photonics. Source arXiv: 2605.09219v1
Covert Signaling for Communication and Sensing over the Bosonic Channels Authors Tianrui Tan, Evan J. D. Anderson, Michael S. Bullock, Boulat A. Bash Published: 05.08.2026 Updated: 06.22.2026 Summary Preventing signal detection in communication and active sensing requires careful control of transmission power. In fact, the square-root laws (SRL) for covert classical and quantum communication and sensing prescribe that the average output energy per channel use scales as $1/sqrt{n}$ for $n$ channel uses. emph{Diffuse} and emph{sparse} signaling achieve this. The former transmits signals whose energy decays as $1/sqrt{n}$ over all $n$ channel uses, which is convenient for mathematical analysis. The latter transmits constant-energy signals only approximately $proptosqrt{n}$ times out of $n$ channel uses, remaining silent on the others. This offers significant practical advantages in compatibility with modern digital transmitters. Here, we study sparse signaling over the lossy thermal-noise bosonic channel, which is a quantum model of many practical channels (including optical, microwave, and radio-frequency). We characterize the input signal state that minimizes detectability. We find an unintuitive optimal quantum state structure: a mixture of just two consecutive photon-number states. In particular, in the low-brightness regime, the optimal signal state is a mixture of vacuum and a single photon. Since these states are generally suboptimal for both communication and active sensing, we explore the resulting trade-off and identify input-power thresholds for transitions between optimizing covertness and performance in communication and sensing tasks. Source arXiv: 2605.08066v2
Covert Signaling for Communication and Sensing over the Bosonic Channels Authors Tianrui Tan, Evan J. D. Anderson, Michael S. Bullock, Boulat A. Bash Published: 05.08.2026 Updated: 05.08.2026 Summary Preventing signal detection in communication and active sensing requires careful control of transmission power. In fact, the square-root laws (SRL) for covert classical and quantum communication and sensing prescribe that the average output power per channel use scales as $1/sqrt{n}$ for $n$ channel uses. Two strategies for achieving this are diffuse and sparse signaling. The former transmits signals with power decaying as $1/sqrt{n}$ on all $n$ channel uses, which is convenient for mathematical analysis. The latter transmits constant-power signals rarely, on approximately $sqrt{n}$ out of $n$ channel uses, while remaining silent on the others. This offers significant practical advantages in compatibility with modern digital transmitters. Here, we study sparse signaling over lossy thermal-noise bosonic channels, which describe quantumly many practical channels (including optical, microwave, and radio-frequency). We characterize the input signal state that minimizes detectability. We find an unintuitive optimal quantum state structure: a mixture of just two consecutive photon-number states. In particular, in the low-brightness regime, the optimal signal state is a mixture of vacuum and a single photon. Since these states are generally suboptimal for both communication and active sensing, we explore the resulting trade-off and identify input-power thresholds for transitions between optimizing for covertness vs. performance in communication and sensing tasks. Source arXiv: 2605.08066v1
Realistic Simulation of Quantum Repeater with Encoding and Classical Error Correction Authors Sagar Patange, Caitao Zhan, Bikun Li, Joaquin Chung, Allen Zang, Liang Jiang, Rajkumar Kettimuthu Published: 05.07.2026 Updated: 05.07.2026 Summary Quantum repeaters are essential for scalable long-distance quantum networking. As quantum information processing moves toward fault-tolerant and error-corrected operations, it becomes increasingly important to study quantum repeaters that also move beyond raw physical entanglement and towards logical entanglement. In this paper, we implement and simulate the quantum repeater with encoding and classical error correction (QRE-CEC) protocol in SeQUeNCe, a discrete-event simulator of quantum networks. The protocol distributes logical Bell pairs, performs encoded entanglement swapping, and uses classical error correction for the decoding of entanglement swapping measurement outcomes to determine Pauli-frame corrections. For this study, we extend SeQUeNCe with a stabilizer-based backend, add support for CSS code-based encoded operations, and integrate gate, measurement, idle decoherence, and state-initialization noise models. Our simulation results show that QRE-CEC suppresses all modeled errors to the second order. Also, QRE-CEC can distribute logical Bell pairs with 0.91 fidelity over a distance of 2000 km under the parameter regimes we study. Beyond protocol-level performance evaluation, our implementation exposes practical simulator and control-plane challenges that are typically abstracted away in theoretical studies. Source arXiv: 2605.06928v1
CLAD: A Clustered Label-Agnostic Federated Learning Framework for Joint Anomaly Detection and Attack Classification Authors Iason Ofeidis, Nikos Papadis, Randeep Bhatia, Leandros Tassiulas, TV Lakshman Published: 05.07.2026 Updated: 05.07.2026 Summary The rapid expansion of the Internet of Things (IoT) and Industrial IoT (IIoT) has created a massive, heterogeneous attack surface that challenges traditional network security mechanisms. While Federated Learning (FL) offers a privacy-preserving alternative to centralized Intrusion Detection Systems (IDS), standard approaches struggle to generalize across diverse device behaviors and typically fail to utilize the vast amounts of unlabeled data present in realistic edge environments. To bridge these gaps, we propose CLAD, a holistic framework that seamlessly incorporates Clustered Federated Learning (CFL) with a novel Dual-Mode Micro-Architecture ($text{DM}^2text{A}$). This unified approach simultaneously tackles the two primary bottlenecks of IoT security: device heterogeneity and label scarcity. The $text{DM}^2text{A}$ component features a shared encoder followed by two branches, enabling joint unsupervised anomaly detection and supervised attack classification; this allows the framework to harvest intelligence from both labeled and unlabeled clients. Concurrently, the clustering component dynamically groups devices with congruent traffic patterns, preventing global model divergence. By carefully combining these elements, CLAD ensures that no data is discarded and distinct operational patterns are preserved. Extensive evaluations demonstrate that this integrated approach significantly outperforms state-of-the-art baselines, achieving a 30% relative improvement in detection performance in scenarios with 80% unlabeled clients, with only half the communication cost. Source arXiv: 2605.06571v1
Non-Markovian delay-assisted sensing with waveguide-coupled quantum emitters Authors Prajit Dhara, Isack Padilla, Saikat Guha, Annyun Das, Kanu Sinha Published: 05.06.2026 Updated: 05.06.2026 Summary We show that in a minimal setup of two waveguide-coupled quantum emitters, separated by long distances and subject to an external field, time-delayed feedback can be a resource for sensing field gradients. While the field gradient induces a detuning between the emitters; the large interatomic separations render the system dynamics non-Markovian. We show that the quantum Fisher information (QFI) for estimating the detuning parameter, and thereby the field gradient, is enhanced in the presence of non-Markovian delay. Such an enhancement can be attributed to the formation of atom-photon quasi-bound states that enable the field to interact with the emitters for longer times, thereby gaining more information about their relative detunings. Additionally, in the presence of delay, the interaction between the emitters is mediated via multiple spectral modes of the field, further enhancing the sensing capabilities of the system. Our results establish non-Markovian time-delayed feedback and multimode reservoirs as a resource for distributed quantum sensing with waveguide-coupled quantum emitters. Source arXiv: 2605.05434v1
GHZ is All You Need: Quantum Sensing with VISTA Authors Oskar Novak, Christos N. Gagatsos, Narayanan Rengaswamy Published: 05.05.2026 Updated: 05.05.2026 Summary Quantum metrology holds the potential to enhance magnetic field sensing beyond current limits. However, in the presence of realistic noise, this advantage degrades to the Standard Quantum Limit. While recent algorithmic and variational techniques attempt to recover this scaling, they are hindered by stringent control requirements on the probe state that are infeasible in the near term, or by barren plateaus and interpretability issues inherent to black-box variational quantum circuits. Here, we introduce Variational Inference and Sensing with Twin Ansätze (VISTA), a closed-loop protocol that combines passive sensing, or where the probe state is left to evolve without any active control, with physics-informed variational optimization. In the VISTA framework, a probe state evolves under a Lindbladian master-equation, and is compared, via the Swap test, to a parameterized “quantum twin”, a shallow quantum circuit designed to mimic the underlying pure-state or Lindbladian master-equation dynamics. By restricting the optimization space to the physical parameters of interest, VISTA circumvents barren plateaus. We demonstrate that by coupling the protocol with a classical optimizer and high shot counts, VISTA can temporarily achieve near-Heisenberg scaling for moderately noisy qubits over a finite range of system sizes. Furthermore, we introduce a Quasi-Normalization technique that sharpens the loss gradients, enabling simultaneous extraction of both the coherent signal $θ$ and the environmental noise rate $γ$ with low absolute error. Finally, we extend VISTA to the multi-parameter vector metrology regime, enabling simultaneous parameter extraction from a transverse-magnetic-field Hamiltonian. By eliminating the need for complex, open-loop control and processing, VISTA offers a highly practical, resource-efficient framework for near- to intermediate-term quantum sensors. Source arXiv: 2605.04203v1
Edge-Based Anisotropic Decoding for Generalized Bicycle Codes Authors Dimitris Chytas, Paul N. Fessatidis, Boulat A. Bash, Bane Vasić Published: 05.04.2026 Updated: 05.04.2026 Summary Quantum low-density parity-check (QLDPC) codes provide non vanishing rates, distance scaling with the blocklength of the code, and facilitate fast iterative decoding because of their sparsity. However, in practice iterative decoding fails to exploit the distance of the code, because it cannot resolve the symmetries imposed by degeneracy. In this work, we provide a graph theoretic characterization of degeneracy for the family of generalized bicycle (GB) codes. This viewpoint shows that harmful degenerate error patterns persist whenever they remain related by automorphisms preserved by the decoder. Motivated by symmetry breaking via graph coloring, we compare three coloring approaches: no coloring, block-coloring, and edge-coloring. For GB codes, we show that edge-coloring can eliminate all automorphisms in low-weight stabilizer-induced subgraphs. We practically realize the coloring schemes as isotropic, block- anisotropic and edge-anisotropic min-sum (MS) decoding. Experimental results show that edge anisotropic min-sum decoding obtains improved performance over isotropic and block anisotropic decoding for several GB codes in a small number of iterations. Source arXiv: 2605.03218v1
Simulation-guided design of an integrated photonic cavity for frequency-multiplexed Spontaneous Parametric Down Conversion Authors Benjamin Szamosfalvi, Michael Raymer, CJ Xin, Leticia Magalhaes, Jarrett Nelson, Marko Lončar, Ryan M. Camacho Published: 05.04.2026 Updated: 05.04.2026 Summary Frequency-multiplexed entangled photon pair sources with narrow bandwidths and high pair generation efficiency are a key enabling technology for quantum networking. We present a simulation-based design study of an integrated photonic racetrack resonator source for spontaneous parametric down-conversion (SPDC) that simultaneously achieves all three properties. The central result is a simulated set of 90 doubly resonant signal/idler frequency-mode pairs with an effective Schmidt number of 89.62, average bandwidths of 1.08 GHz, a mean free spectral range of 51.9 GHz, and a total internal pair-generation-rate efficiency of 1.16 GHz/mW. Under deterministic wavelength-based splitting, the accessible frequency-state Schmidt number is reduced to 44.93. To support these predictions, we derive a closed-form analytical connection between classical cavity parameters (resonant frequencies, decay rates, coupling coefficients) and the quantum joint spectral amplitude and pair generation rate, extending the dispersive-medium quantization formalism of Raymer to the nonlinear optical cavity case. We demonstrate how classical electromagnetic field simulations can be combined with this analytical framework to predict quantum figures of merit for an integrated photonic source prior to fabrication. Fabrication and experimental validation are left for future work. Source arXiv: 2605.03121v1
Simulation-guided design of an integrated photonic cavity for frequency-multiplexed Spontaneous Parametric Down Conversion Authors Benjamin Szamosfalvi, Michael Raymer, CJ Xin, Leticia Magalhaes, Jarrett Nelson, Marko Lončar, Ryan M. Camacho Published: 05.04.2026 Updated: 05.18.2026 Summary Frequency-multiplexed entangled photon pair sources with narrow bandwidths and high pair generation efficiency are a key enabling technology for quantum networking. We present a simulation-based design study of an integrated photonic racetrack resonator source for spontaneous parametric down-conversion (SPDC) that simultaneously achieves all three properties. The central result is a simulated set of 90 doubly resonant signal/idler frequency-mode pairs with an effective Schmidt number of 89.62, average bandwidths of 1.08 GHz, a mean free spectral range of 51.9 GHz, and a total internal pair-generation-rate efficiency of 1.16 GHz/mW. Under deterministic wavelength-based splitting, the accessible frequency-state Schmidt number is reduced to 44.93. To support these predictions, we derive a closed-form analytical connection between classical cavity parameters (resonant frequencies, decay rates, coupling coefficients) and the quantum joint spectral amplitude and pair generation rate, extending the dispersive-medium quantization formalism of Raymer to the nonlinear optical cavity case. We demonstrate how classical electromagnetic field simulations can be combined with this analytical framework to predict quantum figures of merit for an integrated photonic source prior to fabrication. Fabrication and experimental validation are left for future work. Source arXiv: 2605.03121v2
Designing a Satellite Serviced Quantum Network Backbone for Concurrent Global Connectivity Authors Prateek Mantri, Stav Haldar, Albert Williams, Don Towsley Published: 05.04.2026 Updated: 05.04.2026 Summary Satellite-serviced quantum networks pose an architectural problem distinct from classical satellite networking: because entanglement cannot be copied, and long-lived buffering is technologically constrained for near-term devices, useful end-to-end service requires fixed optical ground infrastructure and simultaneous multi-hop path availability. We investigate the design of a satellite-serviced quantum backbone aimed at supporting concurrent global connectivity across a traffic matrix of major population and financial centers under finite waiting-time constraints. Using a discrete-time simulator, we evaluate performance using two architecture-level metrics: (i) time-to-connectivity, and (ii) latency-conditioned average active-link strength. Across a broad parameter sweep, we identify three dominant architectural effects. First, anisotropic ground-station lattices reduce time-to-connectivity relative to longitudinally collapsed and isotropic baselines by aligning ground infrastructure with latitude-dependent satellite access. Second, multi-inclination LEO constellations reduce waiting times for strong connectivity compared to single-inclination constellations at fixed satellite budgets by providing additional visibility for a diverse latitude set. Third, multi-party satellite service policies alleviate per-satellite concurrency bottlenecks and substantially reduce time-to-connectivity at stringent traffic-matrix thresholds. We further show that satellite altitude is the dominant physical lever shaping the visibility–loss trade-off, strongly affecting both connectivity latency and achievable link strength, while orbital plane count and satellite packing provide secondary refinements at fixed altitude. Together, these results delineate the architectural conditions required for scalable, concurrent entanglement connectivity in satellite-serviced quantum networks. Source arXiv: 2605.02164v1
Hierarchical Federated Learning for Networked AI: From Communication Saving to Architecture-Aware Design Authors Seyed Mohammad Azimi-Abarghouyi, Mehdi Bennis, Leandros Tassiulas Published: 05.01.2026 Updated: 05.01.2026 Summary Federated learning (FL) is fundamentally a distributed optimization problem executed by communicating agents with local data, local computation, and partial system visibility. Once FL is viewed through that lens, hierarchy is not merely a scalability mechanism. It becomes the natural place to rethink how distributed optimization should be organized over real multi-tier networks. This article argues that hierarchical federated learning (HFL) should move beyond its common framing as a communication-saving protocol and instead be viewed as an architecture-aware design framework for networked AI. The framework is organized around three coupled design axes: architectural parameters, layer-wise optimization decomposition, and layer-wise communication realization. The first axis determines the coordination geometry of learning through hierarchy depth, layer asymmetry, and layered connectivity. The second determines how the global FL objective is decomposed across layers and highlights modular multi-layer optimization as a major opportunity beyond one dominant method everywhere. The third determines how the distributed optimization is physically realized under heterogeneous communication regimes, from interference-limited lower tiers to reliable upper tiers. A central message is that, in HFL, convergence becomes architecture-dependent: it is directly shaped by the chosen hierarchy, the assigned optimization roles, and the communication mechanisms that connect them. We develop this viewpoint using large-scale wireless edge intelligence as a flagship networked AI setting, then provide a comparative perspective on flat FL, two-tier HFL, and deep HFL together with a regime-oriented design map. The resulting perspective positions HFL as a practical methodology for designing future networked AI systems. Source arXiv: 2605.00931v1
High-fidelity entangling gates and nonlocal circuits with neutral atoms Authors Simon J. Evered, Muqing Xu, Sophie H. Li, Alexandra A. Geim, J. Pablo Bonilla Ataides, Marcin Kalinowski, Dolev Bluvstein, Nishad Maskara, Christian Kokail, Markus Greiner, Vladan Vuletić, Mikhail D. Lukin Published: 04.28.2026 Updated: 04.28.2026 Summary Creation and manipulation of entanglement with low error is essential in quantum information systems. In practice, two-qubit entangling gates constitute a dominant error source, limiting circuit depths and performance in fault-tolerant architectures. Using a neutral-atom quantum processor, we realize entangling CZ gates with a high Rabi frequency smooth-amplitude pulse, employing state-selective readout and qubit reuse for fast calibration, and achieve state-of-the-art fidelities of 99.854(4)% which improve to 99.941(3)% upon loss postselection, with stable performance for 10 hours. We then use these low-error gates in quantum circuits with coherent atom rearrangement. We first benchmark performance by creating and disentangling cluster states, and subsequently implement scrambling circuits featuring longer-range connectivity to study non-locally entangled states generated through chaotic dynamics. These results pave the way towards deep-circuit, efficient fault-tolerant quantum computation. Source arXiv: 2604.25987v1
Quantum-enhanced Network Tomography Authors Yufei Zheng, Zihao Gong, Saikat Guha, Don Towsley Published: 04.28.2026 Updated: 04.28.2026 Summary Network tomography refers to the use of inference techniques for inferring internal network states from end-to-end probes. Quantum probes, implemented by sending blocks of $n$ coherent-state pulses augmented with continuous-variable (CV) squeezing ($n=1$) or weak temporal-mode entanglement ($n>1$) over a lossy channel to a receiver with homodyne detection capabilities, are known to carry information about the channel transmissivity. Assuming a subset of nodes in an optical network is capable of sending and receiving such probes through intermediate nodes with all-optical switching capabilities, we leverage these quantum probes to estimate link transmissivities. To determine how to route the probes in a network, we propose a probe construction algorithm that guarantees link identifiability, while maximizing the number of information orthogonal sets of transmissivities. A set of probes induces a Fisher information matrix (FIM). We then derive two metrics, the determinant of the FIM and the trace of its inverse, to evaluate the performance of the probes. In particular, our results can be used to characterize the quantum improvement in estimating link transmissivities in a general optical network. Source arXiv: 2604.25194v1
Stabilizers for Compiling Logical Circuits under Hardware Constraints Authors Jack Weinberg, Narayanan Rengaswamy Published: 04.27.2026 Updated: 04.27.2026 Summary To implement quantum algorithms on a quantum computer, we must overcome the twin problems of fault-tolerance — how can we realize a relatively noiseless computation by cleverly combining noisy components? — and compilation — how can we realize an arbitrary quantum algorithm given the basic operations available on the quantum device at hand? We show how treating the former problem via error-correcting codes enables greater flexibility in resolving the latter. Specifically, we explicitly leverage the fact that error-correcting codes introduce redundancy which renders physically distinct operators logically indistinguishable. In terms of computation, it suffices to implement any operator logically equivalent to some target, yet from a compilation perspective, certain choices may be preferable to others. Our novel contribution is making this intuition precise in the general setting of the special unitary group. In particular, we describe how to reduce the problem of making a compilation-ideal choice to a least squares problem and provide a closed form solution thereof. Using our framework, it is possible to circumvent inserting costly swaps to adhere to hardware connectivity; instead, we could realize the logical target through a distinct physical Hamiltonian that is natively accessible. We elucidate our approach using the $[[4,2,2]]$ code. We discuss connections to compressed sensing that may pave the way to efficient compilation leveraging physical degrees of freedom. Source arXiv: 2604.25042v1
Networked Realization of Quantum LDPC Codes Authors Swayangprabha Shaw, Narayanan Rengaswamy Published: 04.27.2026 Updated: 04.27.2026 Summary Quantum low-density parity-check (QLDPC) codes with good parameters are promising candidates for low-overhead fault-tolerant quantum computing, but their non-local stabilizers require long-range connectivity and frequent qubit movement, introducing practical challenges. Prior work has studied the networked implementation of topological codes, where each node only holds one or a few qubits of the entire code, and demonstrated competitive performance under practical constraints such as the quality of network-provided entanglement. However, since these codes are already geometrically local, such a networked setting might not be essential. In this work, we propose and study the networked implementation of better QLDPC codes, specifically bivariate bicycle codes due to their similarity to surface codes and the controlled amount of long-range connections in their stabilizers. We begin by recreating networked surface codes in Stim, with one code qubit per node, and provide additional insights into their circuit-level noise performance. We then extend this approach to bipartitions of bivariate bicycle codes, using balanced min-cut partitioning on their combined X-Z Tanner graph to identify optimal qubit splits. For stabilizers spanning nodes, we implement teleported CNOTs and vary the Bell pair fidelity enabling these gates. Through circuit-level noise simulations with BP-OSD decoding, we provide the first insights into networked realizations of these codes and compare their performance with monolithic implementations. We conclude by outlining advantages, limitations, and future directions. Source arXiv: 2604.25026v1
Optimum-Transmission Free-Space Optical Communications Authors Prajit Dhara, Babak N. Saif, Jeffrey H. Shapiro, Saikat Guha Published: 04.25.2026 Updated: 04.25.2026 Summary Slepian developed the Prolate Spheroidal Wavefunction (PSW) spatial-mode basis, which forms the normal modes of the Fresnel-propagation kernel of a free-space optical communications channel bookended by hard-circular apertures. The zero-th order PSW mode has the highest power-transfer eigenvalue, exciting which on the transmitter side therefore maximizes the transmissivity for single-spatial-mode communications. We show that the transmissivity performance of this fundamental PSW mode can be obtained by an aperture-truncated Gaussian beam of an optimized beam waist, despite the two mode shapes deviating from one another in the near-field regime. Source arXiv: 2604.23417v1
Reconfigurable Superconducting Logic for On-Chip Photon Coincidence Detection Authors Gabriel Le Guay, Matteo Castellani, Reed Foster, Francesca Incalza, Alejandro Simon, Owen Medeiros, Phillip D. Keathley, Karl K. Berggren Published: 04.23.2026 Updated: 04.27.2026 Summary Scaling photonic quantum-information platforms requires arrays of superconducting nanowire single-photon detectors (SNSPDs) for feedforward control, in which optical operations are conditioned on preceding Bell-state measurements that typically rely on photon coincidence detections. On-chip superconducting cryotron electronics, performing logic directly on detector outputs and subsequently driving optical modulators, could substantially reduce latency and room-temperature interconnect complexity for feedforward schemes. To date, no cryotron logic gates specifically designed to process SNSPD outputs for quantum applications have been demonstrated. We demonstrate a bias-programmable logic gate based on three nanocryotrons (nTrons), fabricated using the same thin-film technology as SNSPDs. The circuit implements selectable AND (coincidence), XOR (odd-parity), and OR functions on two externally generated electrical pulses at 4.2 K, with bit-error rates below $10^{-3}$, bias margins up to $pm24%$, and operation extending to 25 MHz over narrower bias windows. Moreover, it performs coincidence and odd-parity detection on two co-fabricated SNSPDs’ outputs with bit-error rates below $3.2 times 10^{-2}$. As a proof-of-concept, we show that nTrons can drive capacitive loads up to 1.15 V, potentially enabling compatibility with electro-optic modulators in feedforward schemes. Source arXiv: 2604.22101v2
Reconfigurable Superconducting Logic for On-Chip Photon Coincidence Detection Authors Gabriel Le Guay, Matteo Castellani, Reed Foster, Francesca Incalza, Alejandro Simon, Owen Medeiros, Phillip D. Keathley, Karl K. Berggren Published: 04.23.2026 Updated: 04.23.2026 Summary Scaling photonic quantum-information platforms requires arrays of superconducting nanowire single-photon detectors (SNSPDs) for feedforward control, in which optical operations are conditioned on preceding Bell-state measurements that typically rely on photon coincidence detections. On-chip superconducting cryotron electronics, performing logic directly on detector outputs and subsequently driving optical modulators, could substantially reduce latency and room-temperature interconnect complexity for feedforward schemes. To date, no cryotron logic gates specifically designed to process SNSPD outputs for quantum applications have been demonstrated. We demonstrate a bias-programmable logic gate based on three nanocryotrons (nTrons), fabricated using the same thin-film technology as SNSPDs. The circuit implements selectable AND (coincidence), XOR (odd-parity), and OR functions on two externally generated electrical pulses at 4.2 K, with bit-error rates below $10^{-3}$, bias margins up to $pm24%$, and operation extending to 25 MHz over narrower bias windows. Moreover, it performs coincidence and odd-parity detection on two co-fabricated SNSPDs’ outputs with bit-error rates below $3.2 times 10^{-2}$. As a proof-of-concept, we show that nTrons can drive capacitive loads up to 1.15 V, potentially enabling compatibility with electro-optic modulators in feedforward schemes. Source arXiv: 2604.22101v1
Enhanced Mid-Infrared Single-Photon Detection with Antenna-Coupled Superconducting Nanowires Authors Dip Joti Paul, Stewart Koppell, Gregor G. Taylor, Boris Korzh, Sahil R. Patel, Andrew D. Beyer, Emma E. Wollman, Matthew D. Shaw, Phillip D. Keathley, Karl K. Berggren Published: 04.20.2026 Updated: 04.20.2026 Summary Scaling the photon-detection area of superconducting nanowire single-photon detectors (SNSPDs) has traditionally been achieved by nanowire meandering. However, material inhomogeneities and fabrication-induced defects, such as line-edge roughness, increase with nanowire length, leading to reduced internal photon-detection efficiency and elevated dark-count rates. This trade-off becomes increasingly pronounced as nanowires are scaled to sub-100 nm widths and sub-5 nm thicknesses required for mid- to far-infrared sensitivity. Here, we demonstrate an antenna-coupled SNSPD architecture that enhances the effective photon-detection area without increasing nanowire length. A crossed bowtie antenna integrated with an 80 nm-wide, 3 nm-thick WSi nanowire yields 15.7$times$ increase in effective detection area at 7.4 $μ$m compared to a bare nanowire of identical geometric footprint, while maintaining the same internal detection efficiency and dark-count rate. Antenna coupling improves noise-equivalent power and provides a more scalable route to increasing photon-detection area than conventional meander geometries, offering performance benefits for applications in astronomy, biological imaging, and molecular spectroscopy. Source arXiv: 2604.18155v1
Enhanced Mid-Infrared Single-Photon Detection with Antenna-Coupled Superconducting Nanowires Authors Dip Joti Paul, Stewart Koppell, Gregor G. Taylor, Boris Korzh, Sahil R. Patel, Andrew D. Beyer, Emma E. Wollman, Matthew D. Shaw, Phillip D. Keathley, Karl K. Berggren Published: 04.20.2026 Updated: 07.16.2026 Summary Scaling the photon-detection area of superconducting nanowire single-photon detectors (SNSPDs) has traditionally been achieved by nanowire meandering. However, material inhomogeneities and fabrication-induced defects, such as line-edge roughness, increase with nanowire length, leading to reduced internal photon-detection efficiency and elevated dark-count rates. This trade-off becomes increasingly pronounced as nanowires are scaled to sub-100 nm widths and sub-5 nm thicknesses required for mid- to far-infrared sensitivity. Here, we demonstrate an antenna-coupled SNSPD architecture that enhances the effective photon-detection area without increasing nanowire length. A crossed bowtie antenna integrated with an 80 nm-wide, 3 nm-thick WSi nanowire yields 15.7$times$ increase in effective detection area at 7.4 $μ$m compared to a bare nanowire of identical geometric footprint, while maintaining the same internal detection efficiency and dark-count rate. Antenna coupling provides a scalable approach to increasing photon-detection area while reducing the noise-equivalent power, offering performance benefits for applications in astronomy, biological imaging, and molecular spectroscopy. Source arXiv: 2604.18155v2
Resource-Efficient Quantum-Enhanced Compressive Imaging via Quantum Classical co-Design Authors Haowei Shi, Visuttha Manthamkarn, Christopher M. Jones, Zheshen Zhang, Quntao Zhuang Published: 04.17.2026 Updated: 04.17.2026 Summary Quantum sensing can enhance imaging performance by reducing measurement noise below the classical limit, thereby improving the signal-to-noise ratio (SNR) of acquired data. In conventional quantum imaging schemes, squeezing is applied independently to each pixel or spatial mode, leading to a quantum resource cost that scales linearly with image dimension. This approach implicitly separates quantum enhancement from classical post-processing, treating them as independent layers. In this work, we demonstrate that integrating quantum resource allocation with the guidance from classical compressive imaging, via co-design between the quantum hardware layer and the classical software layer, substantially reduces the required quantum resources. We employ principal component analysis (PCA) to identify a low-dimensional principal component subspace for measurement and apply squeezing selectively to the most informative spatial modes corresponding to these principal components. Our numerical experiments show that high-accuracy image classification and high-fidelity image reconstruction can be achieved with significantly fewer squeezed modes compared to pixel-wise squeezing. Our results establish a joint quantum classical co-design framework for resource-efficient quantum-enhanced imaging. Source arXiv: 2604.16662v1
Noise factor of Brillouin amplifiers Authors John H. Dallyn, Nils T. Otterstrom, Matt Eichenfield, Peter T. Rakich, Ryan O. Behunin Published: 04.14.2026 Updated: 04.14.2026 Summary Stimulated Brillouin scattering (SBS), an optical nonlinearity arising from photon-phonon interactions, has formed the basis for a large class of optical signal processing devices, including Brillouin amplifiers. A limiting factor of such amplifiers is the noise due to thermal-mechanical fluctuations that the phonons imprint on the optical signal. Prior work has either inferred or experimentally observed a noise factor ($F$) that depends only on the thermal occupation of the phonons ($Fapprox 1+n_{th}$). We show that this noise factor results naturally from a Hamiltonian-based spatio-temporal coupled mode treatment in the limit of large Brillouin amplification and when phonon propagation is neglected. Moreover, this theoretical framework allows us to extend our treatment to a much larger and more representative parameter space for emerging SBS systems; specifically, this analysis accounts for the forward or backward nature of the scattering process and the effects of phonon propagation, optical loss, and small Brillouin gains. Our results demonstrate that the noise factor can deviate radically from $Fapprox 1+n_{th}$ for a host of modern SBS devices, especially those in which phonon propagation significantly changes the coupled mode dynamics. Source arXiv: 2604.12906v1
Three-body interactions in Rydberg lattices Authors Rhine Samajdar, Mikhail D. Lukin, Valentin Walther Published: 04.13.2026 Updated: 04.13.2026 Summary Programmable arrays of neutral Rydberg atoms are one of the leading platforms today for scalable quantum simulation and computation. In these systems, the dipole-dipole interactions between the individual atoms, or qubits, typically result in binary — i.e., two-body — couplings. In this work, we develop an experimentally accessible scheme for engineering three-body interactions in Rydberg lattices. Such strong three-body couplings can fundamentally modify the underlying physics compared to systems with only two-body interactions: we demonstrate this, in particular, by systematically investigating the effective many-body Hamiltonian and its emergent quantum phases. This capability paves the way for the quantum simulation of a broader class of correlated models of condensed matter and high-energy physics. Source arXiv: 2604.11870v1
Scalable Neural Decoders for Practical Fault-Tolerant Quantum Computation Authors Andi Gu, J. Pablo Bonilla Ataides, Mikhail D. Lukin, Susanne F. Yelin Published: 04.09.2026 Updated: 04.09.2026 Summary Quantum error correction (QEC) is essential for scalable quantum computing. However, it requires classical decoders that are fast and accurate enough to keep pace with quantum hardware. While quantum low-density parity-check codes have recently emerged as a promising route to efficient fault tolerance, current decoding algorithms do not allow one to realize the full potential of these codes in practical settings. Here, we introduce a convolutional neural network decoder that exploits the geometric structure of QEC codes, and use it to probe a novel “waterfall” regime of error suppression, demonstrating that the logical error rates required for large-scale fault-tolerant algorithms are attainable with modest code sizes at current physical error rates, and with latencies within the real-time budgets of several leading hardware platforms. For example, for the $[144, 12, 12]$ Gross code, the decoder achieves logical error rates up to $sim 17$x below existing decoders – reaching logical error rates $sim 10^{-10}$ at physical error $p=0.1%$ – with 3-5 orders of magnitude higher throughput. This decoder also produces well-calibrated confidence estimates that can significantly reduce the time overhead of repeat-until-success protocols. Taken together, these results suggest that the space-time costs associated with fault-tolerant quantum computation may be significantly lower than previously anticipated. Source arXiv: 2604.08358v1
A Family of Open Time-Series Foundation Models for the Radio Access Network Authors Ioannis Panitsas, Leandros Tassiulas Published: 04.05.2026 Updated: 04.05.2026 Summary The Radio Access Network (RAN) is evolving into a programmable and disaggregated infrastructure that increasingly relies on AI-native algorithms for optimization and closed-loop control. However, current RAN intelligence is still largely built from task-specific models tailored to individual functions, resulting in model fragmentation, limited knowledge sharing across tasks, poor generalization, and increased system complexity. To address these limitations, we introduce TimeRAN, a unified multi-task learning framework for time-series modeling in the RAN. TimeRAN leverages a lightweight time-series foundation model with few task-specific heads to learn transferable representations that can be efficiently adapted across diverse tasks with limited supervision. To enable large-scale pretraining, we further curate and open-source TimeRAN DataPile, the largest time-series corpus for RAN analytics to date, comprising over 355K time series and 0.56B measurements across diverse telemetry sources, protocol layers, and deployment scenarios. We evaluate TimeRAN across a comprehensive set of RAN analytics tasks, including anomaly detection, classification, forecasting, and imputation, and show that it achieves state-of-the-art performance with minimal or no task-specific fine-tuning. Finally, we integrate TimeRAN into a proof-of-concept 5G testbed and demonstrate that it operates efficiently with limited resource requirements in real-world scenarios. Source arXiv: 2604.04271v1
Understanding Intrinsic Loss in Thin-Film Lithium Niobate Ring Resonators via Adiabatic Coupling Authors Xinrui Zhu, Hana K. Warner, Yunxiang Song, Donald Witt, Marko Loncar Published: 04.02.2026 Updated: 04.02.2026 Summary Thin-film lithium niobate (TFLN) has emerged as a versatile integrated photonics platform, combining strong electro-optic and nonlinear effects. Among TFLN devices, ring resonators play a central role in filtering, modulation, and nonlinear optical processes. However, intrinsic loss, which ultimately limits ring performance, is most often summarized by single-valued metrics, and its statistical variability across resonances has received limited attention. Here, we show that intrinsic loss rates in monolithic TFLN ring resonators follow a statistical distribution, comprising a baseline loss and a tail arising from discrete loss events. This behavior is revealed by characterizing 2233 resonances, using an adiabatic waveguide-ring coupling architecture that selectively excites the fundamental mode and yields clean spectra in the ultra-high-Qi regime. We find the most probable intrinsic loss rate ki = 2 pi x 10.4 MHz, indicating operation in a low-loss regime comparable to state-of-the-art thick silicon nitride platforms. Source arXiv: 2604.01922v1
Unlocking Open-Player-Modeling-enhanced Game-Based Learning: The Open Player Socially Analytical Intelligence Architecture Authors Zhiyu Lin, Boyd Fox, Devon Mckee, Sai Siddartha Maram, Jiahong Li, Tyler Sorensen, Brian K. Smith, Roger Azevedo, Jichen Zhu, Magy Seif El-Nasr Published: 03.27.2026 Updated: 03.27.2026 Summary Game-Based Learning (GBL) is a learner-engaging pedagogical methodology, yet adapting games to heterogeneous learners requires transparent, real-time Open Player Models (OPMs). We contribute to the community Open Player Socially Analytical Intelligence (OPSAI), an architecture implementing OPM beyond conceptual frameworks and validated in a GBL application. It decouples gameplay telemetry and analysis from the game engine and automatically derives pedagogically actionable insights, supporting the transparency of computational player models while making them accessible to players. OPSAI comprises three logical layers: a Frontend that both provides the GBL experience and collects information needed for analytics; a stateless Backend that hosts transparent analytics services producing reflective prompts, recommendations, and visualization guides; and a two-tier Log Storage that balances heavy raw gameplay data with lightweight reference indices for low-latency queries. By feeding analytics outputs back into the game interface, OPSAI closes the feedback loop between play and learning, empowering teachers, researchers, and learners alike. We further showcase OPSAI with a full deployment on the Parallel GBL environment, featuring live play traces, peer comparisons, and personalized suggestions, demonstrating a reusable blueprint for future educational games. Source arXiv: 2603.26915v1
T Count as a Numerically Solvable Minimization Problem Authors Marc Grau Davis, Ed Younis, Mathias Weiden, Hyeongrak Choi, Dirk Englund Published: 03.26.2026 Updated: 05.15.2026 Summary We present a formulation of the problem of finding the smallest T -Count circuit that implements a given unitary as a binary search over a sequence of continuous minimization problems, and demonstrate that these problems are numerically solvable in practice. We reproduce best-known results for synthesis of circuits with a small number of qubits, and push the bounds of the largest circuits that can be solved for in this way. Additionally, we show that circuit partitioning can be used to adapt this technique to be used to optimize the T -Count of circuits with large numbers of qubits by breaking the circuit into a series of smaller sub-circuits that can be optimized independently. Source arXiv: 2603.25101v2
T Count as a Numerically Solvable Minimization Problem Authors Marc Grau Davis, Ed Younis, Mathias Weiden, Hyeongrak Choi, Dirk Englund Published: 03.26.2026 Updated: 03.26.2026 Summary We present a formulation of the problem of finding the smallest T -Count circuit that implements a given unitary as a binary search over a sequence of continuous minimization problems, and demonstrate that these problems are numerically solvable in practice. We reproduce best-known results for synthesis of circuits with a small number of qubits, and push the bounds of the largest circuits that can be solved for in this way. Additionally, we show that circuit partitioning can be used to adapt this technique to be used to optimize the T -Count of circuits with large numbers of qubits by breaking the circuit into a series of smaller sub-circuits that can be optimized independently. Source arXiv: 2603.25101v1
Visible Spectral-Domain Optical Coherence Tomography for Photonic Integrated Circuits Characterization Authors Yin Min Goh, Chao Li, Yunchan Hwang, Helaman Flores, Mahmoud Jalali Mehrabad, James G. Fujimoto, Dirk R. Englund Published: 03.25.2026 Updated: 03.25.2026 Summary Visible photonic integrated circuits underpin applications ranging from AR/VR to quantum control, yet lack a high-resolution, nondestructive diagnostic comparable to the optical frequency-domain reflectometry used in infrared silicon photonics. Here we adapt spectral-domain optical coherence tomography to measure guided-mode back-reflections in visible PICs. Broadband visible light injected into a circuit generates back-reflections that interfere with a depth-referencing local oscillator, and the resulting spectral fringes are recorded on a spectrometer. We validate the approach by resolving multiple round-trip echoes in a waveguide-coupled ring resonator using only single-port access. We then extend it to circuits integrated with diamond quantum micro-chiplets, clearly resolving input and output facets as well as PIC–QMC transition regions. The system achieves shot-noise-limited sensitivity, 50 dB dynamic range, 8 um axial resolution in silicon nitride, and a 2 mm imaging depth at 6 dB roll-off. SD-OCT therefore provides a practical, high-resolution diagnostic for visible PICs that uses a broadband probe source and requires only single-port optical access, enabling rapid characterization of propagation loss, backscattering, and dispersion. Source arXiv: 2603.23815v1
Rethinking Quantum Networking with Advances in Fiber Technology Authors Prateek Mantri, Michael S. Bullock, Aditya Tripathi, Robert Kwolek, Rajveer Nehra, Don Towsley Published: 03.24.2026 Updated: 03.24.2026 Summary Recent comparisons of quantum repeater protocols have highlighted the strong near-term potential of multiplexed two-way architectures for long-distance quantum communication. At the same time, advances in hollow-core fiber (HCF) technology motivate a re-examination of the physical transmission medium as an architectural lever in quantum network design. In this work, we compare emerging anti-resonant HCFs against conventional silica single-mode fibers (SMFs) in multiplexed two-way quantum repeater networks. We evaluate their performance under both telecom and memory-native transmission, accounting for frequency-conversion overheads, coupling efficiencies, memory decoherence, and operational noise. We find that HCF significantly outperforms SMF across a wide range of regimes. With memory-native transmission, HCF yields up to an order of magnitude improvement in secret-key rate per channel use under realistic conversion efficiencies. Even at telecom wavelengths, HCF enables larger optimal repeater spacing, improving rate–cost tradeoffs and reducing repeater requirements. We further quantify the role of memory quality, hardware efficiency, detector and conversion losses, and two-qubit gate noise in shaping these gains. These results show that recent advances in HCF materially expand the design space of practical terrestrial quantum repeater networks. Source arXiv: 2603.23718v1
Observation of microscopic domain effects in the metal-insulator transition of thin-film NdNiO$_3$ Authors Lucy S. Nathwani, Anne Ruperto, Ashvini Vallipuram, Abigail Y. Jiang, Grace A. Pan, Dan Ferenc Segedin, Ari B. Turkiewicz, Charles M. Brooks, Jarad A. Mason, Qichen Song, Julia A. Mundy Published: 03.22.2026 Updated: 03.22.2026 Summary Perovskite oxides display correlated electrical, magnetic, and thermal properties that can be further tuned in the thin-film limit, making them contenders for next-generation electronics. Measuring thermal transport in thin films is challenging, because traditional techniques are dominated by the substrate. Here, frequency-domain thermoreflectance (FDTR) of an epitaxial NdNiO$_3$ thin film reveals a sharp change in out-of-plane thermal conductivity across the metal-insulator transition. Complementary frequency-domain photoreflectance (FDPR) reveals a large change in ambipolar diffusivity of photoexcited carriers. While the in-plane electrical resistance shows large hysteresis, out-of-plane thermal and charge transport shows negligible hysteresis. We attribute this discrepancy to anisotropy in the percolation of nanoscale domains across the transition as the film thickness approaches the domain length scale. We establish FDTR and FDPR as sensitive probes of quantum material phase transitions and highlight NdNiO$_3$ for thermal control and memory applications. Source arXiv: 2603.21405v1
Fast Real-Axis Eliashberg Calculations: Full-bandwidth solutions beyond the constant density of states approximation Authors Alejandro Simon, James Shi, Dominik Spath, Eva Kogler, Reed Foster, Emma Batson, Pedro N. Ferreira, Mihir Sahoo, Phillip D. Keathley, Warren E. Pickett, Rohit Prasankumar, Karl K. Berggren, Christoph Heil Published: 03.18.2026 Updated: 03.18.2026 Summary Experimentally relevant signatures of superconductivity require access to real-frequency quantities, such as the spectral functions, optical response, and transport properties, yet Migdal-Eliashberg calculations are commonly performed on the imaginary axis and then analytically continued, a step that is numerically delicate and can obscure physically relevant spectral features. Here we present a practical route to solving the finite-temperature Migdal-Eliashberg equations directly on the real-frequency axis, while retaining the effects from the full-bandwidth electronic structure. Our formulation accounts for particle-hole asymmetry through an energy-dependent electronic density of states, avoiding the constant density of states approximation often used in real-axis calculations, and includes a static screened Coulomb contribution. We introduce an efficient numerical technique to solve the Migdal-Eliashberg integrals whose computational cost scales linearly with the real-frequency grid, making high-resolution, full-bandwidth real-axis calculations feasible and providing direct access to the interacting Green’s function and derived observables without analytic continuation. As an illustration, we apply the method to H$_{3}$S, where a van-Hove singularity near the Fermi level produces strong particle-hole asymmetry. The full-bandwidth solution yields noticeably different spectra than the constant density of states approximation and brings the superconducting gap and lineshapes into closer agreement with experiment, highlighting when band-structure details are essential. Furthermore, the methods presented here open the door to time-dependent, nonequilibrium simulations within Eliashberg theory. Source arXiv: 2603.18199v1
Ultrafast dynamics and light-induced superconductivity from first principles Authors Alejandro Simon, James Shi, Eva Kogler, Reed Foster, Dominik Spath, Emma Batson, Pedro N. Ferreira, Mihir Sahoo, Rohit Prasankumar, Phillip D. Keathley, Karl K. Berggren, Christoph Heil Published: 03.18.2026 Updated: 03.18.2026 Summary Experiments on superconducting materials have unveiled unique emergent properties when they are driven far from equilibrium. However, a quantitative first-principles treatment that describes experimental observations is lacking. In this work, we develop an ab-initio model for the nonequilibrium response of optically irradiated superconducting films within the framework of conventional electron-phonon-mediated superconductivity, leveraging new numerical techniques to solve the Migdal-Eliashberg equations directly on the real-frequency axis. This enables us to quantitatively reproduce the optical response of superconducting films in pump-probe experiments and validate our approach on measurements of the differential reflectance of Pb and LaH$_{10}$ in response to a pump excitation. Similar calculations performed on the alkali-doped fulleride K$_3$C$_{60}$ reveal that a photo-induced superconducting state is generated after irradiation by an ultrafast mid-infrared pulse of sufficient intensity, as reported in prior experimental work. The enhancement in this framework is attributed to the excitation of quasiparticles to energies resonant with the strongest electron-phonon coupling in K$_3$C$_{60}$, in close analogy to the mechanism for enhancement of superconductivity under microwave irradiation, explaining the nature of the photo-induced superconducting state and elucidating the subsequent quasiparticle and phonon dynamics. Our results suggest that photo-induced superconductivity is accessible in more materials than previously recognized. We demonstrate this by performing calculations on calcium-intercalated graphite, CaC$_6$, and predict a similar photo-induced superconducting gap. Source arXiv: 2603.18182v1
Boosted linear-optical measurements on single-rail qubits with unentangled ancillas Authors Aqil Sajjad, Isack Padilla, Saikat Guha Published: 03.17.2026 Updated: 03.17.2026 Summary Any quantum state of the radiation field, sliced in small non-overlapping space-time bins is a collection of single-rail qubits, each spanning the vacuum and single-photon Fock state of a mode. Quantum logic on these qubits would enable arbitrary measurements on information-bearing light, but is hard due to the lack of strong nonlinearities. With unentangled ancilla single-rail qubits, an $8$-port interferometer and photon detection, we show any single-rail qubit measurement in the $XY$ Bloch plane is realizable with success probability $147/256$, which beats the prior-known $1/2$ limit. Source arXiv: 2603.16795v1
Programmable pixel-mode linear interferometers using multi-plane light conversion Authors Mushkan Sureka, Itay Ozer, Wenhua He, Michael R. Grace, Chaohan Cui, Saikat Guha Published: 03.16.2026 Updated: 03.16.2026 Summary Programmable linear optical interferometers are a core primitive in optical signal processing, quantum information processing, and photonic computing. Existing photonic-integrated implementations realize arbitrary $M$-mode unitaries using Mach–Zehnder-interferometer meshes whose footprint and accumulated loss scale with $O(M^2)$ optical components. Here we analyze and experimentally demonstrate a programmable architecture for implementing linear optical transformations directly on spatially tiled free-space pixel modes using multi-plane light conversion (MPLC). In this architecture, $M$ spatial modes arranged on a transverse lattice undergo a unitary transformation and are mapped to $M$ output modes of identical geometry through a sequence of programmable phase masks separated by free-space propagation segments. Numerical simulations show that arbitrary $M$-mode unitaries can be compiled to a desired high fidelity using a number of phase planes that scales approximately linearly with $M$. Using a spatial-light-modulator-based MPLC, we experimentally demonstrate programmable interferometers acting on up to $16$ spatial pixel modes, including tunable beamsplitters, Hadamard unitaries, spatial permutations, boosted-Bell-measurement unitaries, and partial unitaries on select subsets of modes. These results establish MPLC-based pixel-mode interferometers as a promising architecture for programmable linear optics with applications in classical and quantum optical interconnects, photonic switching, and quantum information processing. Source arXiv: 2603.15836v1
Noise and dynamics in acoustoelectric waveguides Authors Ryan O. Behunin, Andrew Shepherd, Ruoyu Yuan, Taylor Ray, Matthew J. Storey, Peter T. Rakich, Nils T. Otterstrom, Matt Eichenfield Published: 03.16.2026 Updated: 03.16.2026 Summary We present a quantum field theoretic formulation of acoustoelectric interactions in waveguide-like systems of arbitrary cross-section. Building on an open quantum systems approach, we derive a unified description of plasmon-phonon coupling that incorporates dissipation, noise, and the influence of drift currents. Our analysis captures both bulk and surface plasmon modes, highlighting how drift currents Doppler-shift plasmonic resonances and reshape the phonon noise spectrum. The resulting Heisenberg-Langevin equations yield closed-form expressions for frequency shifts, gain, and noise power spectra, enabling direct evaluation of performance metrics such as the noise factor in acoustoelectric amplifiers and oscillators. In the appropriate limits, this framework reproduces known results while extending them to complex geometries. Source arXiv: 2603.15482v1
Microwave spin resonance in epitaxial thin films of spin liquid candidate TbInO3 Authors Sandesh S. Kalantre, Johanna Nordlander, Margaret A. Anderson, Julia A. Mundy, David Goldhaber-Gordon Published: 03.15.2026 Updated: 03.15.2026 Summary Minimizing the energy of a many body system tends to favor order, but classical frustration and quantum fluctuations destabilize that order. The tension between these effects can produce exotic quantum states of matter. Quantum spin liquid (QSL) states emerge in models of localized magnetic moments where the crystal lattice connectivity frustrates ordering, and the exchange interaction of neighboring spins strengthens quantum fluctuations. Experimentally identifying a QSL in a real material is challenging from the lack of an order parameter. Piecing together evidence from varied techniques is necessary for diagnosing the nature of the ground state — QSL or otherwise — of a frustrated spin system. In this work, we use coplanar superconducting resonators to probe magnetic excitations in epitaxially grown thin films of a spin liquid candidate TbInO3. Adapting microwave techniques from the field of circuit quantum electrodynamics, we measure responses of these thin films whose volume is too low for applying conventional bulk techniques. In-plane susceptibility extracted from the spin resonance signal indicates extreme frustration of magnetic order down to 20 mK, over two orders of magnitude lower than the Curie-Weiss energy scale. Through a crystal field analysis, we identify the doublet eigenstates comprising the ground state. As a consequence of improper ferroelectricity, Tb moments split into two flavors with distinct g-factors reflecting the local crystal field environment of each site. Spin-orbit coupling, crystal fields, magnetic frustration and improper ferroelectricity distinctively combine to shape the magnetic ground state of TbInO3. This work establishes a measurement technique using superconducting resonators to probe thin films of frustrated magnets, and applies this technique towards building a coherent understanding of the magnetic properties of TbInO3. Source arXiv: 2603.14545v1
Digital dissipative state preparation for frustration-free gapless quantum systems Authors Johannes Feldmeier, Yu-Jie Liu, Mikhail D. Lukin, Soonwon Choi Published: 03.10.2026 Updated: 03.10.2026 Summary Preparing algebraically correlated ground states of quantum many-body systems is an important, yet challenging task for quantum simulation. We introduce a protocol that employs local projective measurements and unitary feedback for frustration-free gapless systems. Our approach prepares a priori unknown ground states in time that scales polynomially with system size. We analytically show the performance our protocol for the dynamics of a single-particle; we argue the same mechanism generalizes to many-body systems based on the physics of quasiparticles. Our theory predicts that a transient cooling dynamics directly reveals the system’s universal critical properties. In particular, the state preparation time is linear in the inverse of the finite-size gap (up to log correction) when the system’s dynamical critical exponent is larger or equal the effective spatial dimension explored by the quasiparticles. We verify these predictions in numerical simulations of ferromagnetic Heisenberg models in one- and two dimensions, a Fredkin spin chain, and a two-dimensional model of resonating valence bond states. Our protocol stabilizes gapless many-body ground states fully digitally without requiring analog rotations, enabling access to high-fidelity states beyond conventional adiabatic approaches in near-term experiments. Source arXiv: 2603.10119v1
Heterogeneously Integrated Diamond-on-Lithium Niobate Quantum Photonic Platform Authors Sophie W. Ding, Chang Jin, Zixi Li, Nicholas Achuthan, Kazuhiro Kuruma, Xinghan Guo, Brandon Grinkemeyer, David D. Awschalom, Nazar Delegan, F. Joseph Heremans, Alexander A. High, Marko Loncar Published: 03.09.2026 Updated: 03.09.2026 Summary Diamond photonics has enabled efficient interfaces for quantum memories and is predicted to be a critical component of quantum networks. However, scalable network architectures require spatial, temporal, and spectral control of photons, which relies on nonlinear and electro-optic functionalities that diamond alone cannot provide. Here, we demonstrate heterogeneous integration of a thin-film lithium niobate (TFLN) platform, which has strong chi-2 nonlinearity and electro-optic effects, with thin diamond films. We demonstrate high-Q diamond photonic crystal cavities (Q factors exceeding 5×10^4 at 735 nm) that are lithographically aligned with TFLN photonic backbone and critically coupled to it. This allows us to realize low-loss diamond-TFLN “escalators” (loss ~1 dB/coupler) that support efficient light transfer between them. At cryogenic temperatures (5K), we can collect photons emitted from silicon vacancies (SiVs) embedded within the diamond structure via the TFLN photonic circuit. This approach establishes a scalable route toward integrated photonic circuits for practical quantum networking and other technologies. Source arXiv: 2603.08609v1
Benchmark for Assessing Olfactory Perception of Large Language Models Authors Eftychia Makri, Nikolaos Nakis, Laura Sisson, Gigi Minsky, Leandros Tassiulas, Vahid Satarifard, Nicholas A. Christakis Published: 03.08.2026 Updated: 03.08.2026 Summary Here we introduce the Olfactory Perception (OP) benchmark, designed to assess the capability of large language models (LLMs) to reason about smell. The benchmark contains 1,010 questions across eight task categories spanning odor classification, odor primary descriptor identification, intensity and pleasantness judgments, multi-descriptor prediction, mixture similarity, olfactory receptor activation, and smell identification from real-world odor sources. Each question is presented in two prompt formats, compound names and isomeric SMILES, to evaluate the effect of molecular representations. Evaluating 21 model configurations across major model families, we find that compound-name prompts consistently outperform isomeric SMILES, with gains ranging from +2.4 to +18.9 percentage points (mean approx +7 points), suggesting current LLMs access olfactory knowledge primarily through lexical associations rather than structural molecular reasoning. The best-performing model reaches 64.4% overall accuracy, which highlights both emerging capabilities and substantial remaining gaps in olfactory reasoning. We further evaluate a subset of the OP across 21 languages and find that aggregating predictions across languages improves olfactory prediction, with AUROC = 0.86 for the best performing language ensemble model. LLMs should be able to handle olfactory and not just visual or aural information. Source arXiv: 2604.00002v1
Quantum Hamlets: Distributed Compilation of Large Algorithmic Graph States Authors Anthony Micciche, Naphan Benchasattabuse, Andrew McGregor, Michal Hajdušek, Rodney Van Meter, Stefan Krastanov Published: 03.06.2026 Updated: 03.06.2026 Summary We investigate the problem of compiling the generation of graph states to arbitrarily many distributed homogeneous quantum processing units (QPUs), providing a scalable partitioning algorithm and graph state generation protocol to minimize the number of Bell pairs required. To this goal, we consider the problem of balanced k graph partitioning with the objective of minimizing the sizes of the maximum matchings between partitions, a more natural measure of entanglement compared to the naive but common metric of cut edges. We show that our heuristic algorithm, BURY, partitions graph states to require fewer Bell pairs for generation than state-of-the-art k partition algorithms. Furthermore, we show that BURY reduces the cut-rank of the partitions, demonstrating that the partitioning found by our algorithm is likely to minimize the Bell pair utilization of any future improved distributed graph state generation protocol. Additionally, we discuss how one could straightforwardly apply our methods to the dynamic case where the graph state generation and measurement are performed concurrently. Our study of the balanced minimum maximum matching k partition problem and the heuristic algorithm we design provides a scalable foundation for reducing quantum network overhead for distributed measurement-based quantum computation (MBQC), as well as any scheme where distributed graph state generation is desired. Source arXiv: 2603.06387v1
Quantum Hamlets: Distributed Compilation of Large Algorithmic Graph States Authors Anthony Micciche, Naphan Benchasattabuse, Andrew McGregor, Michal Hajdušek, Rodney Van Meter, Stefan Krastanov Published: 03.06.2026 Updated: 05.03.2026 Summary We investigate the problem of compiling the generation of graph states to arbitrarily many distributed homogeneous quantum processing units (QPUs), providing a scalable partitioning algorithm and graph state generation protocol to minimize the number of Bell pairs required. Current approaches focus on the naive metric of cut edges to estimate the quantum communication cost. We show that the problem of balanced k graph partitioning, with the objective of minimizing the sizes of the maximum matchings between the partitions, leads to lower entanglement requirements across partitions. Our heuristic algorithm, BURY, partitions graph states to require fewer Bell pairs for generation than state-of-the-art k partition algorithms. Furthermore, we show that BURY reduces the cut-rank of the partitions, demonstrating that the partitioning found by our algorithm is likely to minimize the Bell pair utilization of any future improved distributed graph state generation protocol. We also discuss how our methods apply to the dynamic case where the graph state generation and measurement are performed concurrently. Our compilation approach provides a scalable foundation for reducing quantum network overhead for distributed measurement-based quantum computation (MBQC), as well as any scheme where distributed graph state generation is desired. Source arXiv: 2603.06387v2
Challenges in Synchronous & Remote Collaboration Around Visualization Authors Matthew Brehmer, Maxime Cordeil, Christophe Hurter, Takayuki Itoh, Wolfgang Büschel, Mahmood Jasim, Arnaud Prouzeau, David Saffo, Lyn Bartram, Sheelagh Carpendale, Chen Zhu-Tian, Andrew Cunningham, Tim Dwyer, Samuel Huron, Masahiko Itoh, Alark Joshi, Kiyoshi Kiyokawa, Hideaki Kuzuoka, Bongshin Lee, Gabriela Molina León, Harald Reiterer, Bektur Ryskeldiev, Jonathan Schwabish, Brian A. Smith, Yasuyuki Sumi, Ryo Suzuki, Anthony Tang, Yalong Yang, Jian Zhao Published: 03.06.2026 Updated: 03.06.2026 Summary We characterize 16 challenges faced by those investigating and developing remote and synchronous collaborative experiences around visualization. Our work reflects the perspectives and prior research efforts of an international group of 29 experts from across human-computer interaction and visualization sub-communities. The challenges are anchored around five collaborative activities that exhibit a centrality of visualization and multimodal communication. These activities include exploratory data analysis, creative ideation, visualization-rich presentations, joint decision making grounded in data, and real-time data monitoring. The challenges also reflect the changing dynamics of these activities in the face of recent advances in extended reality (XR) and artificial intelligence (AI). As an organizing scheme for future research at the intersection of visualization and computer-supported cooperative work, we align the challenges with a sequence of four sets of research and development activities: technological choices, social factors, AI assistance, and evaluation. Source arXiv: 2603.05871v1
An Optimization Framework for Monitor Placement in Quantum Network Tomography Authors Athira Kalavampara Raghunadhan, Matheus Guedes De Andrade, Don Towsley, Indrakshi Dey, Daniel Kilper, Nicola Marchetti Published: 03.06.2026 Updated: 03.06.2026 Summary Quantum Network Tomography (QNT) offers a framework for end-to-end quantum channel characterization by strategically placing monitor nodes within the network. Building upon prior work on single-monitor placement, we study optimal monitor placement and measurement assignments for channel parameter estimation in arbitrary quantum networks. Using an n-node star network as a baseline, we analyze multi-monitor configurations and show that distributing monitors across end nodes can achieve estimation performance comparable to a monitor placed at the hub. Estimation precision is quantified using the Quantum Fisher Information Matrix (QFIM), with channel parameters inferred via Maximum Likelihood Estimation (MLE) and benchmarked against the Quantum Cramer-Rao Bound (QCRB). To generalize, we develop two Integer Linear Program (ILP) formulations: one maximizing estimation accuracy (QF), and another jointly optimizing accuracy and monitoring overhead (QMF). Unlike QF, QMF prevents monitor overloading, enabling scalability and parallelism. We prove optimality for star and analyze applicability to tree-structured quantum networks. Source arXiv: 2603.05777v1
The Evolution of Magnetism in a Thin Film Pyrochlore Ferromagnetic Insulator Authors Margaret A. Anderson, Megan E. Goh, Yang Zhang, Kyeong-Yoon Baek, Michael Schulze, Mario Brutzam, Christoph Liebald, Chris Lygouras, Dan Ferenc Segedin, Aaron M. Day, Zubia Hasan, Donald A. Walko, Hua Zhou, Peter Bencok, Alpha T. N'Diaye, Charles M. Brooks, Ismail El Baggari, John T. Heron, S. M. Koopayeh, Daniel Rytz, Christo Guguschev, Julia A. Mundy Published: 03.05.2026 Updated: 03.05.2026 Summary The pyrochlore vanadates are compelling candidates for next-generation dissipationless devices. Lu2V2O7 and Y2V2O7 are ferromagnetic insulators (Tc ~ 70 K) that are believed to exhibit the magnon Hall effect and are expected to host topological magnons. Their completely dissipationless magnon edge states could be harnessed to realize low-power information transport in spintronic or magnonic devices. As a crucial step in the realization of devices, we synthesize the first thin films of pyrochlore Y2V2O7 on isostructural Y2Ti2O7 substrates and explore the evolution of their magnetic properties down to the ultrathin limit. All films are insulating ferromagnets with transition temperatures of up to the bulk value (Tc ~ 68 K) that decrease with thickness according to finite-size effects. Our films also exhibit a change in anisotropy from in-plane to out-of-plane easy axis coincident with the development of partial strain relaxation and nonzero magnetic hysteresis in an applied field. This evolution demonstrates the impact of strain on magnetic anisotropy and paves the way to tunable magnon topology. Source arXiv: 2603.05717v1
Quantum advantages for syndrome-aware noisy logical observable estimation Authors Kento Tsubouchi, Hyukgun Kwon, Liang Jiang, Nobuyuki Yoshioka Published: 03.05.2026 Updated: 06.05.2026 Summary Recent progress in fault-tolerant quantum computing suggests that leveraging error-syndrome information at the logical layer can substantially improve performance, including the estimation of logical observables from noisy states. In this work, based on quantum estimation theory, we develop an information-theoretic framework to quantify the utility of error syndromes for noisy logical observable estimation. We distinguish two operational regimes of such syndrome-aware protocols: classical protocols, in which the logical measurement basis is fixed and syndrome information is used only in classical post-processing, and quantum protocols, in which the logical quantum control can be tailored to depend on the observed error syndrome. For classical syndrome-aware protocols, we prove a universal limitation: on average, syndrome information can improve the effective logical error rate by at most a factor of two, implying at most a quadratic reduction in sampling overhead. In contrast, once syndrome-conditioned quantum control is permitted, we demonstrate that the effective logical error rate decays exponentially with the number of code blocks. These findings provide fundamental guidance for designing future fault-tolerant architectures that actively exploit syndrome records rather than discarding them after decoding. Source arXiv: 2603.05145v2
Quantum advantages for syndrome-aware noisy logical observable estimation Authors Kento Tsubouchi, Hyukgun Kwon, Liang Jiang, Nobuyuki Yoshioka Published: 03.05.2026 Updated: 03.05.2026 Summary Recent progress in fault-tolerant quantum computing suggests that leveraging error-syndrome information at the logical layer can substantially improve performance, including the estimation of logical observables from noisy states. In this work, based on quantum estimation theory, we develop an information-theoretic framework to quantify the utility of error syndromes for noisy logical observable estimation. We distinguish two operational regimes of such syndrome-aware protocols: classical protocols, in which the logical measurement basis is fixed and syndrome information is used only in classical post-processing, and quantum protocols, in which the logical quantum control can be tailored to depend on the observed error syndrome. For classical syndrome-aware protocols, we prove a universal limitation: on average, syndrome information can improve the effective logical error rate by at most a factor of two, implying at most a quadratic reduction in sampling overhead. In contrast, once syndrome-conditioned quantum control is permitted, we exhibit settings in which the effective logical error rate decays exponentially with the number of logical qubits. These findings provide fundamental guidance for designing future fault-tolerant architectures that actively exploit syndrome records rather than discarding them after decoding. Source arXiv: 2603.05145v1
Variational Quantum Transduction Authors Pengcheng Liao, Haowei Shi, Quntao Zhuang Published: 03.04.2026 Updated: 03.04.2026 Summary Quantum transducers are critical for quantum interconnect, enabling coherent signal transfer across disparate frequency domains. Beyond material and device advances, protocol design has become a powerful means to improve transduction. We introduce a variational quantum transduction (VQT) framework that employs variational tools from near-term quantum computing to systematically optimize protocol performance. As a variational quantum circuit framework, VQT is not plagued by known training issues such as barren plateau, because a small-scale problem is sufficient for substantial advantage and training only needs to be done once to configure a VQT system. Maximizing the quantum information rate within this framework yields protocols that surpass all known schemes in their respective classes. For non-adaptive protocols, VQT exceeds the performance envelopes of Gottesman-Kitaev-Preskill (GKP)-based and entanglement-assisted approaches. In the adaptive setting, VQT provides only a marginal improvement over Gaussian feedforward strategies, indicating that Gaussian adaptive transduction is already close to optimal. With increasingly universal quantum control, VQT provides a systematic path toward optimal quantum transduction. Source arXiv: 2603.03642v1
Rate-Fidelity Tradeoffs in All-Photonic and Memory-Equipped Quantum Switches Authors Panagiotis Promponas, Leonardo Bacciottini, Paul Polakos, Gayane Vardoyan, Don Towsley, Leandros Tassiulas Published: 03.03.2026 Updated: 03.03.2026 Summary Quantum entanglement switches are a key building block for early quantum networks, and a central design question is whether near-term devices should use only flying photons or also incorporate quantum memories. We compare two architectures: an all-photonic entanglement generation switch (EGS) that repeatedly attempts Bell-state measurements (BSM) without storing qubits, and a quantum memory-equipped switch that buffers entanglement and triggers measurements only when heralded connectivity is available (herald-then-swap control). These two designs trade off simple, memoryless operation that avoids decoherence and memory-induced latency against heralding-based control that buffers entanglement to use BSMs more efficiently. We formalize both models under a common hardware abstraction and characterize their achievable rate-fidelity regions, yielding a benchmarking methodology that translates hardware and protocol parameters into network-level performance. Numerical evaluation quantifies the rate-fidelity tradeoffs of both models, identifies operating regions in which each architecture dominates, and shows how hardware and protocol knobs can be tuned to meet application-specific targets. Source arXiv: 2603.02610v1
