Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Conference on Lasers and Electro-Optics

Quantum key distribution with 1.25 Gbps clock synchronization

Joshua C. Bienfang, Alex Gross, Alan Mink, Barry Hershman, Anastase Nakassis, Xiao Hong Tang, Richang Lu, David H. Su, Charles W. Clark, Carl J. Williams, E. W. Hagley, Jesse Wen

Published Jan 1, 2004• 1 citation
Publisher

Abstract

We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results.A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm.Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate.System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors.With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.This work was performed for the U.S.

DOI
10.1364/iqec.2004.ipda8

Related papers

Quantum key distribution with 1.25 Gbps clock synchronization

Joshua C. Bienfang, A. J. Gross, Alan Mink +9 more

We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results. A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm. Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate. System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors. With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.

arXiv:quant-ph/0405097•Optics Express•Jan 1, 2004•128 citations

Quantum key distribution with 1.25 Gbps clock synchronization

Joshua C. Bienfang, Alex J. Gross, Alan Mink +6 more

Clock recovery techniques at 1.25 Gbps enable continuous quantum key distribution at demonstrated sifted-key rates exceeding 1 Mbps. This rate is two orders of magnitude faster than has been reported previously, and serves to enhance both the data encryption capabilities and the distance over which a QKD system can operate. Full-text article is not available.

Frontiers in Optics•Jan 1, 2004•10 citations

Free-space quantum key distribution at GHz repetition rates

Joshua C. Bienfang, Daniel J. Rogers, Alessandro Restelli +7 more

Quantum key distribution (QKD) can produce secure cryptographic key for use in symmetric cryptosystems. By adopting clock-recovery techniques from modern telecommunications practice we have demonstrated a free-space quantum key distribution system operating at a transmission rate of 625 MHz at 850 nm. The transmission rate of this system is ultimately limited by the timing resolution of the single-photon avalanche photodiodes (SPADs), and we present a solution to take advantage of SPADs with higher timing resolution that can enable repetition rates up to 2.5 GHz. We also show that with high-repetition-rate sub-clock gating these higher-resolution SPADs can reduce the system's exposure to solar background photons, thus reducing the quantum-bit error rate (QBER) and improving system performance.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 8, 2007•0 citations

High-speed photon counting techniques for broadband quantum key distribution

Daniel J. Rogers, Joshua C. Bienfang, Alan Mink +7 more

ABSTRACT Quantum Cryptography has demonstrated the potential for ultra-secure communications. However, with quantum-channel transmission rates in the MHz range, typical link losses and signal-to-noise ratios have resulted in key-production rates that are impractical for continuous one-time-pad encryption of high-bandwidth communications. We have developed high-speed data handling electronics that support quantum-channel transmission rates up to 1.25 GHz. This system has demonstrated error-corrected and privacy-amplified key rates above 1 Mbps over a free-space link. While the transmission rate is ultimately limited by timi ng jitter in the single-photon avalanche photodiodes (SPADs), we find the timing resolution of silicon SPADs sufficient to operate efficiently with temporal gates as short as 100 ps. We have developed systems to implement such high-resolution gating in our system, and anticipate the attendant reduction in noise to produce significantly higher secret-key bitrates. Keywords: Single-photon detection, quantum key distribution, avalanche photodiode

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Oct 18, 2006•1 citation

Free-space quantum cryptography in the H-alpha Fraunhofer window

Daniel J. Rogers, Joshua C. Bienfang, Alan Mink +7 more

Free-space Quantum key distribution (QKD) has shown the potential for the practical production of cryptographic key for ultra-secure communications. The performance of any QKD system is ultimately limited by the signal to noise ratio on the single-photon channel, and over most useful communications links the resulting key rates are impractical for performing continuous one-time-pad encryption of today's broadband communications. We have adapted clock and data recovery techniques from modern telecommunications practice, combined with a synchronous classical free-space optical communications link operating in parallel, to increase the repetition rate of a free-space QKD system by roughly 2 orders of magnitude over previous demonstrations. We have also designed the system to operate in the H-alpha Fraunhofer window at 656.28 nm, where the solar background is reduced by roughly 7 dB. This system takes advantage of high efficiency silicon single-photon avalanche photodiodes with <50ps timing resolution that are expected to enable operation at a repetition rate of 2.5 GHz. We have identified scalable solutions for delivering sustained one-time-pad encryption at 10 Mbps, thus making it possible to integrate quantum cryptography into first-generation Ethernet protocols.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 31, 2006•28 citations

Comment on "Quantum key distribution with 1.25 Gbps clock synchronization" by J.C. Bienfang et al., quant-ph/0405097

Richard Hughes, J. E. Nordholt

We analyze the significance for quantum key distribution (QKD) of free-space quantum communications results reported in a recent paper (J. C. Bienfang et al., quant-ph/0405097, hereafter referred to as "Bienfang et al."), who contrast the quantum communications rate of their partial QKD implementation (which does not produce cryptographically useful shared, secret keys) over a short transmission distance, with the secret bit rates of previous full QKD implementations over much longer distances. We show that when a cryptographically relevant comparison with previous results is made, the system described by Bienfang et al. would offer no advantages for QKD, contrary to assertions in their paper and in spite of its high clock rate. Further, we show that the claim made by Bienfang et al. that "high transmission rates serve ... to extend the distance over which a QKD system can operate" is incorrect. Our analysis illustrates an important aspect of QKD that is too often overlooked in experiments: the sifted bit rate can be a highly misleading indicator of the performance of a QKD system.

arXiv:quant-ph/0407050•Jul 6, 2004•1 citation
We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results.A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm.Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate.System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors.With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.This work was performed for the U.S.
We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results. A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm. Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate. System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors. With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.
Quantum key distribution (QKD) can produce secure cryptographic key for use in symmetric cryptosystems. By adopting clock-recovery techniques from modern telecommunications practice we have demonstrated a free-space quantum key distribution system operating at a transmission rate of 625 MHz at 850 nm. The transmission rate of this system is ultimately limited by the timing resolution of the single-photon avalanche photodiodes (SPADs), and we present a solution to take advantage of SPADs with higher timing resolution that can enable repetition rates up to 2.5 GHz. We also show that with high-repetition-rate sub-clock gating these higher-resolution SPADs can reduce the system's exposure to solar background photons, thus reducing the quantum-bit error rate (QBER) and improving system performance.
ABSTRACT Quantum Cryptography has demonstrated the potential for ultra-secure communications. However, with quantum-channel transmission rates in the MHz range, typical link losses and signal-to-noise ratios have resulted in key-production rates that are impractical for continuous one-time-pad encryption of high-bandwidth communications. We have developed high-speed data handling electronics that support quantum-channel transmission rates up to 1.25 GHz. This system has demonstrated error-corrected and privacy-amplified key rates above 1 Mbps over a free-space link. While the transmission rate is ultimately limited by timi ng jitter in the single-photon avalanche photodiodes (SPADs), we find the timing resolution of silicon SPADs sufficient to operate efficiently with temporal gates as short as 100 ps. We have developed systems to implement such high-resolution gating in our system, and anticipate the attendant reduction in noise to produce significantly higher secret-key bitrates. Keywords: Single-photon detection, quantum key distribution, avalanche photodiode
Free-space Quantum key distribution (QKD) has shown the potential for the practical production of cryptographic key for ultra-secure communications. The performance of any QKD system is ultimately limited by the signal to noise ratio on the single-photon channel, and over most useful communications links the resulting key rates are impractical for performing continuous one-time-pad encryption of today's broadband communications. We have adapted clock and data recovery techniques from modern telecommunications practice, combined with a synchronous classical free-space optical communications link operating in parallel, to increase the repetition rate of a free-space QKD system by roughly 2 orders of magnitude over previous demonstrations. We have also designed the system to operate in the H-alpha Fraunhofer window at 656.28 nm, where the solar background is reduced by roughly 7 dB. This system takes advantage of high efficiency silicon single-photon avalanche photodiodes with <50ps timing resolution that are expected to enable operation at a repetition rate of 2.5 GHz. We have identified scalable solutions for delivering sustained one-time-pad encryption at 10 Mbps, thus making it possible to integrate quantum cryptography into first-generation Ethernet protocols.
We analyze the significance for quantum key distribution (QKD) of free-space quantum communications results reported in a recent paper (J. C. Bienfang et al., quant-ph/0405097, hereafter referred to as "Bienfang et al."), who contrast the quantum communications rate of their partial QKD implementation (which does not produce cryptographically useful shared, secret keys) over a short transmission distance, with the secret bit rates of previous full QKD implementations over much longer distances. We show that when a cryptographically relevant comparison with previous results is made, the system described by Bienfang et al. would offer no advantages for QKD, contrary to assertions in their paper and in spite of its high clock rate. Further, we show that the claim made by Bienfang et al. that "high transmission rates serve ... to extend the distance over which a QKD system can operate" is incorrect. Our analysis illustrates an important aspect of QKD that is too often overlooked in experiments: the sifted bit rate can be a highly misleading indicator of the performance of a QKD system.