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.
We demonstrate electro-optic modulators realized in low-loss thin-film
lithium tantalate with superior DC-stability (<1 dB power fluctuation from
quadrature with 12.1 dBm input) compared to equivalent thin-film lithium
niobate modulators (5 dB fluctuation) over 46 hours.
Practical quantum networks will require quantum nodes consisting of many
memory qubits. This in turn will increase the complexity of the photonic
circuits needed to control each qubit and will require strategies to multiplex
memories and overcome the inhomogeneous distribution of their transition
frequencies. Integrated photonics operating at visible to near-infrared (VNIR)
wavelength range, compatible with the transition frequencies of leading quantum
memory systems, can provide solutions to these needs. In this work, we realize
a VNIR thin-film lithium niobate (TFLN) integrated photonics platform with the
key components to meet these requirements. These include low-loss couplers ($$ 20 dB extinction), and high-bandwidth electro-optic
modulators ($>$ 50 GHz). With these devices we demonstrate high-efficiency and
CW-compatible frequency shifting ($>$ 50 $%$ efficiency at 15 GHz), as well as
simultaneous laser amplitude and frequency control through a nested modulator
structure. Finally, we highlight an architecture for multiplexing quantum
memories using the demonstrated TFLN components, and outline how this platform
can enable a 2-order of magnitude improvement in entanglement rates over single
memory nodes. Our results demonstrate that TFLN can meet the necessary
performance and scalability benchmarks to enable large-scale quantum nodes.
The distribution of entanglement in quantum networks is typically approached
under idealized assumptions such as perfect synchronization and centralized
control, while classical communication is often neglected. However, these
assumptions prove impractical in large-scale networks. In this paper, we
present a pragmatic perspective by exploring two minimal asynchronous
protocols: a parallel scheme generating entanglement independently at the link
level, and a sequential scheme extending entanglement iteratively from one
party to the other. Our analysis incorporates non-uniform repeater spacings and
classical communications and accounts for quantum memory decoherence. We
evaluate network performance using metrics such as entanglement bit rate,
end-to-end fidelity, and secret key rate for entanglement-based quantum key
distribution. Our findings suggest the sequential scheme’s superiority due to
comparable performance with the parallel scheme, coupled with simpler
implementation. Additionally, we propose a cutoff strategy to improve
performance by discarding attempts with prolonged memory idle time, effectively
eliminating low-quality entanglement links. Finally, we apply our methods to
the real-world topology of SURFnet and report the performance as a function of
memory coherence time.
Bell-state measurement (BSM) on entangled states shared between quantum
repeaters is the fundamental operation used to route entanglement in quantum
networks. Performing BSMs on Werner states shared between repeaters leads to
exponential decay in the fidelity of the end-to-end Werner state with the
number of repeaters, necessitating entanglement distillation. Generally,
entanglement routing protocols use emph{probabilistic} distillation techniques
based on local operations and classical communication. In this work, we use
quantum error correcting codes (QECCs) for emph{deterministic} entanglement
distillation to route Werner states on a chain of repeaters. To maximize the
end-to-end distillable entanglement, which depends on the number and fidelity
of end-to-end Bell pairs, we utilize global link-state knowledge to determine
the optimal policy for scheduling distillation and BSMs at the repeaters. We
analyze the effect of the QECC’s properties on the entanglement rate and the
number of quantum memories. We observe that low-rate codes produce
high-fidelity end-to-end states owing to their excellent error-correcting
capability, whereas high-rate codes yield a larger number of end-to-end states
but of lower fidelity. The number of quantum memories used at repeaters
increases with the code rate as well as the classical computation time of the
QECC’s decoder.
See all the latest pre-published papers from our team of collaborators.
