CQN is developing the entire technology stack to reliably carry quantum data across the globe, serving diverse applications across many user groups simultaneously... spurring new technology industries and a competitive marketplace of quantum service providers and application developers.
Join us for a World Quantum Day panel organized jointly by the Perimeter Institute and Quantum Ethics Project and sponsored by CQN. Our discussion will feature Raymond LaFlamme (Institute for Quantum Computing), Zeki Seskir (Karlsruhe Institute of Technology (KIT)) Jean Olemou (Leap Quantik) Taqi Raza (Center for Quantum Networks) and Joan Arrow (Quantum Ethics Project, Center for Quantum Networks). The panel will discuss how […]
Narayanan Rengaswamy is a an assistant professor in the Electrical and Computer Engineering program at the University of Arizona.He also works at the NSF Engineering Research Center for Quantum Networks (CQN) in the university. He discusses his research focuses on quantum error correction and fault tolerance.
Optica Quantum is a new online-only journal dedicated to high-impact results in quantum information science and technology (QIST), as enabled by optics and photonics. Optica Quantum will publish its first issue in September 2023. Its scope will encompass theoretical and experimental research as well as technological advances in and applications of quantum optics. In addition, the Journal will […]
We are pleased to announce the appointment of Julie Des Jardins as the new Director for Diversity and Culture of Inclusion (DCI) within CQN. Dr. Des Jardins is a cultural historian, educator, and DEI practitioner who examines gender, race, and intersectional identity in American culture, particularly in academia, athletics, politics, and STEM. She has also […]
A short video highlighting CQN’s work in building the quantum Internet was featured at the American Physical Society (APS) meeting in Las Vegas in March 2023. The six-minute video features laboratory footage from multiple CQN campuses and interviews with director Saikat Guha, as well as investigators Linran Fan, Dirk Englund, Jane Bambauer, Don Towsley, and […]
All nine courses can be found on our YouTube channel in the CQN Winter School for Quantum Networks playlist. Slides associated with the courses can be found here.
Leandros Tassiulas has won one of thirteen JP Morgan Chase Faculty Research Awards for his work on artificial intelligence. The awards aim to “empower the best research thinkers across AI today” in order to “advance cutting-edge AI research to solve real-world problems.” Leandros is one of CQN’s primary investigators at Yale, which is one of […]
The team behind the University of Arizona’s $99-million Grand Challenges Research Building (GCRB) is wrapping up a seven-level lab structure. The new building will house around a half-dozen different cutting-edge functions and programs in an extremely tight footprint within just 2.5 years. Among other operations, GCRB will serve as the new headquarters of the Center […]
Check out additional stories and events from the Center for Quantum Networks.
As Low Earth Orbit (LEO) satellite mega constellations continue to be
deployed for satellite internet and recent successful experiments in
satellite-based quantum entanglement distribution emerge, a natural question
arises: How should we coordinate transmissions and design scalable scheduling
policies for a quantum satellite internet? In this work, we consider the
problem of transmission scheduling in quantum satellite networks subject to
resource constraints at the satellites and ground stations. We show that the
most general problem of assigning satellites to ground station pairs for
entanglement distribution is NP-hard. We then propose four heuristic algorithms
and evaluate their performance for Starlink mega constellation under various
amount of resources and placements of the ground stations. We find that the
maximum number of receivers necessary per ground station grows very slowly with
the total number of deployed ground stations. Our proposed algorithms,
leveraging optimal weighted b-matching and the global greedy heuristic,
outperform others in entanglement distribution rate, entanglement fidelity, and
handover cost metrics. While we develop these scheduling algorithms, we have
also designed a software system to simulate, visualize, and evaluate satellite
mega-constellations for entanglement distribution.
Quantum networks (QNs) distribute entangled states to enable distributed
quantum computing and sensing applications. However, in such QNs, quantum
switches (QSs) have limited resources that are highly sensitive to noise and
losses and must be carefully allocated to minimize entanglement distribution
delay. In this paper, a QS resource allocation framework is proposed, which
jointly optimizes the average entanglement distribution delay and entanglement
distillation operations, to enhance the end-to-end (e2e) fidelity and satisfy
minimum rate and fidelity requirements. The proposed framework considers
realistic QN noise and includes the derivation of the analytical expressions
for the average quantum memory decoherence noise parameter, and the resulting
e2e fidelity after distillation. Finally, practical QN deployment aspects are
considered, where QSs can control 1) nitrogen-vacancy (NV) center SPS types
based on their isotopic decomposition, and 2) nuclear spin regions based on
their distance and coupling strength with the electron spin of NV centers. A
simulated annealing metaheuristic algorithm is proposed to solve the QS
resource allocation optimization problem. Simulation results show that the
proposed framework manages to satisfy all users rate and fidelity requirements,
unlike existing distillation-agnostic (DA), minimal distillation (MD), and
physics-agnostic (PA) frameworks which do not perform distillation, perform
minimal distillation, and does not control the physics-based NV center
characteristics, respectively. Furthermore, the proposed framework results in
around 30% and 50% reductions in the average e2e entanglement distribution
delay compared to existing PA and MD frameworks, respectively. Moreover, the
proposed framework results in around 5%, 7%, and 11% reductions in the average
e2e fidelity compared to existing DA, PA, and MD frameworks, respectively.
Distributed Quantum Computing (DQC) provides a means for scaling available
quantum computation by interconnecting multiple quantum processor units (QPUs).
A key challenge in this domain is efficiently allocating logical qubits from
quantum circuits to the physical qubits within QPUs, a task known to be
NP-hard. Traditional approaches, primarily focused on graph partitioning
strategies, have sought to reduce the number of required Bell pairs for
executing non-local CNOT operations, a form of gate teleportation. However,
these methods have limitations in terms of efficiency and scalability.
Addressing this, our work jointly considers gate and qubit teleportations
introducing a novel meta-heuristic algorithm to minimise the network cost of
executing a quantum circuit. By allowing dynamic reallocation of qubits along
with gate teleportations during circuit execution, our method significantly
enhances the overall efficacy and potential scalability of DQC frameworks. In
our numerical analysis, we demonstrate that integrating qubit teleportations
into our genetic algorithm for optimising circuit blocking reduces the required
resources, specifically the number of EPR pairs, compared to traditional graph
partitioning methods. Our results, derived from both benchmark and randomly
generated circuits, show that as circuit complexity increases – demanding more
qubit teleportations – our approach effectively optimises these teleportations
throughout the execution, thereby enhancing performance through strategic
circuit partitioning. This is a step forward in the pursuit of a global quantum
compiler which will ultimately enable the efficient use of a ‘quantum data
center’ in the future.
We propose a circuit architecture for a dissipatively error-corrected GKP
qubit. The device consists of a high-impedance LC circuit coupled to a
Josephson junction and a resistor via a controllable switch. When the switch is
activated via a particular family of stepwise protocols, the resistor absorbs
all noise-induced entropy, resulting in dissipative error correction of both
phase and amplitude errors. This leads to an exponential increase of qubit
lifetime, reaching beyond 10ms in simulations with near-feasible parameters. We
show that the lifetime remains exponentially long in the presence of extrinsic
noise and device/control imperfections (e.g., due to parasitics and finite
control bandwidth) under specific thresholds. In this regime, lifetime is
likely only limited by phase slips and quasiparticle tunneling. We show that
the qubit can be read out and initialized via measurement of the supercurrent
in the Josephson junction. We finally show that the qubit supports native
self-correcting single-qubit Clifford gates, where dissipative error-correction
of control noise leads to exponential suppression of gate infidelity.
See all the latest pre-published papers from our team of collaborators.
