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

Physical Review X

High-Rate Measurement-Device-Independent Quantum Communication without Optical Reference Light

Shan-Feng Shao, Lai Zhou, Jinping Lin, Mariella Minder, Chengfang Ge, Yuan-Mei Xie, Ao Shen, Zhengyu Yan, Hua‐Lei Yin, Zhiliang L. Yuan

Published May 23, 2025• 28 citations
Publisher

Abstract

In the realm of long-distance quantum communication, asynchronous measurement-device-independent quantum key distribution (AMDI-QKD) stands out for its experimental simplicity and high key rate generation. Despite these advantages, there exists a challenge in finding a balance between simplifying the laser system further and achieving high key rates. To address this challenge, we have devised a postmeasurement compensation scheme to accurately estimate the mutual frequency offset between two compact lasers using just the announced quantum-signal detection results, thereby obviating the need for optical reference light. As a result, we demonstrate an AMDI-QKD system operating at 2.5 GHz and achieving secure key rates (SKRs) of 537 and 101 kbit / s at distances of 100 and 201 km, respectively, showcasing a significant key rate improvement compared to similar setups. By leveraging ultrastable lasers, we achieve the highest SKRs with measurement-device-independent security within the 100–400-km range. Over 100 km, we reach a remarkable key rate of 1.03 Mbit / s , which could enable real-time one-time-pad video encryption. These findings render AMDI-QKD as a promising contender for the establishment of high performance and cost-effective large-scale intercity quantum networks.

DOI
10.1103/physrevx.15.021066

Related papers

Advantages of Asynchronous Measurement-Device-Independent Quantum Key Distribution in Intercity Networks

Yuan-Mei Xie, Jun-Lin Bai, Yu-Shuo Lu +3 more

The alternative variant of measurement-device-independent quantum key distribution (MDI QKD), called asynchronous MDI QKD or mode-pairing MDI QKD, offers similar repeaterlike rate-loss scaling but has the advantage of simple technology implementation by exploiting an innovative postmeasurement pairing technique. We herein present an evaluation of the practical aspects of decoy-state asynchronous MDI QKD. To determine its effectiveness, we analyze the optimal method of decoy-state calculation and examine the impact of asymmetrical channels and multiuser networks. Our simulations show that, under realistic conditions, aynchronous MDI QKD can furnish the highest key rate with MDI security as compared to other QKD protocols over distances ranging from 50 to 480 km. At fiber distances of 50 and 100 km, the key rates attain 6.02 and 2.29 Mbps, respectively, which are sufficient to facilitate real-time one-time-pad video encryption. Our findings indicate that experimental implementation of asynchronous MDI QKD in intercity networks can be both practical and efficient.

arXiv:2302.14349•Physical Review Applied•May 22, 2023•30 citations

Improved model on asynchronous measurement-device-independent quantum key distribution with realistic devices

Ming-Shuo Sun, Chunhui Zhang, Rui Zhang +3 more

Abstract In principle, the asynchronous measurement-device-independent quantum key distribution (AMDI-QKD) can surpass the key rate capacity without phase tracking and phase locking. However, practical imperfections in sources or detections would dramatically depress its performance. Here, we present an improved model on AMDI-QKD to reduce the influence of these imperfections, including intensity fluctuation, the afterpulse effect, and the dead time of detectors. Furthermore, we carry out corresponding numerical simulations. Simulation results show that, by implementing our present work, it can have more than 100 km longer secure transmission distance and one order of magnitude enhancement in the key generation rate after 320 km compared with the standard method. Moreover, our model can still break the Pirandola–Laurenza–Ottaviani–Banchi (PLOB) bound even under realistic experimental conditions.

Chinese Physics B•Aug 30, 2024•2 citations

Experimental Quantum Communication Overcomes the Rate-Loss Limit without Global Phase Tracking

Lai Zhou, Jinping Lin, Yuan-Mei Xie +4 more

Secure key rate (SKR) of point-point quantum key distribution (QKD) is fundamentally bounded by the rate-loss limit. Recent breakthrough of twin-field (TF) QKD can overcome this limit and enables long distance quantum communication, but its implementation necessitates complex global phase tracking and requires strong phase references that not only add to noise but also reduce the duty cycle for quantum transmission. Here, we resolve these shortcomings, and importantly achieve even higher SKRs than TF-QKD, via implementing an innovative but simpler measurement-device-independent QKD that realizes repeaterlike communication through asynchronous coincidence pairing. Over 413 and 508 km optical fibers, we achieve finite-size SKRs of 590.61 and 42.64 bit/s, which are respectively 1.80 and 4.08 times of their corresponding absolute rate limits. Significantly, the SKR at 306 km exceeds 5 kbit/s and meets the bitrate requirement for live one-time-pad encryption of voice communication. Our work will bring forward economical and efficient intercity quantum-secure networks.

arXiv:2212.14190•Physical Review Letters•Jun 20, 2023•154 citations

Adaptive Measurement-Device-Independent Quantum Key Distribution

Noor, Mah, Toor, A. H.

In theory, quantum key distribution (QKD) promises unconditional secure generation of the key between two remote participants, based on the laws of quantum physics. However, because of the imperfections in the real-life implementation of QKD, this promise fails. To fill the gap between the theory and implementation of QKD, different protocols have been proposed. One of them is measurement device independent (MDI) QKD, which can be implemented using present-day technology and generates a reasonable key rate. The protocol works perfectly fine for intracity communication. However, the transmission distance is not enough, so that it can replace intercity communication. For that, adaptive measurement device-independent (AMDI) QKD has been proposed. So, the present-day classical communication network such as the internet can be replaced with its quantum version. Till the date, AMDI-QKD has been implemented with threshold detectors. In this paper, we replaced threshold detectors with photon-number resolving detectors, thus making the protocol more realistic. We calculated the secret key rate for the case and discussed its dependence on transmission distance. We also discussed the dependence of the sifted key rate and quantum bit error rate (QBER) on the transmission distance.

arXiv:2505.05500•May 6, 2025•0 citations

Experimental Mode-Pairing Measurement-Device-Independent Quantum Key Distribution without Global Phase Locking

Hao-Tao Zhu, Yizhi Huang, Hui Liu +11 more

In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication parties. Despite their advantageous performance over long communication distances, the requirement of phase locking between two remote lasers is technically challenging. By adopting the recently proposed mode-pairing idea, we realize high-performance quantum key distribution without global phase locking. Using two independent off-the-shelf lasers, we show a quadratic key-rate improvement over the conventional measurement-device-independent schemes in the regime of metropolitan and intercity distances. For longer distances, we also boost the key rate performance by 3 orders of magnitude via 304 km commercial fiber and 407 km ultralow-loss fiber. We expect this ready-to-implement high-performance scheme to be widely used in future intercity quantum communication networks.

arXiv:2208.05649•Physical Review Letters•Jan 17, 2023•110 citations

Post-measurement pairing quantum key distribution with local optical frequency standard

Chengfang Ge, Lai Zhou, Jinping Lin +3 more

Abstract The idea of post-measurement coincidence pairing simplifies substantially long-distance, repeater-like quantum key distribution (QKD) by eliminating the need for tracking the differential phase of the users’ lasers. However, optical frequency tracking remains necessary and can become a severe burden in future deployment of multi-node quantum networks. Here, we resolve this problem by referencing each user’s laser to an absolute frequency standard and demonstrate a practical post-measurement pairing QKD with excellent long-term stability. We confirm the setup’s repeater-like behavior and achieve a finite-size secure key rate (SKR) of 15.94 bit s−1 over 504 km fiber, which overcomes the absolute repeaterless bound by 1.28 times. Over a fiber length 100 km, the setup delivers an impressive SKR of 285.68 kbit s−1. Our work paves the way towards an efficient muti-user quantum network with the local frequency standard.

arXiv:2407.14771•Quantum Science and Technology•Nov 27, 2024•8 citations
In the realm of long-distance quantum communication, asynchronous measurement-device-independent quantum key distribution (AMDI-QKD) stands out for its experimental simplicity and high key rate generation. Despite these advantages, there exists a challenge in finding a balance between simplifying the laser system further and achieving high key rates. To address this challenge, we have devised a postmeasurement compensation scheme to accurately estimate the mutual frequency offset between two compact lasers using just the announced quantum-signal detection results, thereby obviating the need for optical reference light. As a result, we demonstrate an AMDI-QKD system operating at 2.5 GHz and achieving secure key rates (SKRs) of 537 and 101 kbit / s at distances of 100 and 201 km, respectively, showcasing a significant key rate improvement compared to similar setups. By leveraging ultrastable lasers, we achieve the highest SKRs with measurement-device-independent security within the 100–400-km range. Over 100 km, we reach a remarkable key rate of 1.03 Mbit / s , which could enable real-time one-time-pad video encryption. These findings render AMDI-QKD as a promising contender for the establishment of high performance and cost-effective large-scale intercity quantum networks.
The alternative variant of measurement-device-independent quantum key distribution (MDI QKD), called asynchronous MDI QKD or mode-pairing MDI QKD, offers similar repeaterlike rate-loss scaling but has the advantage of simple technology implementation by exploiting an innovative postmeasurement pairing technique. We herein present an evaluation of the practical aspects of decoy-state asynchronous MDI QKD. To determine its effectiveness, we analyze the optimal method of decoy-state calculation and examine the impact of asymmetrical channels and multiuser networks. Our simulations show that, under realistic conditions, aynchronous MDI QKD can furnish the highest key rate with MDI security as compared to other QKD protocols over distances ranging from 50 to 480 km. At fiber distances of 50 and 100 km, the key rates attain 6.02 and 2.29 Mbps, respectively, which are sufficient to facilitate real-time one-time-pad video encryption. Our findings indicate that experimental implementation of asynchronous MDI QKD in intercity networks can be both practical and efficient.
Abstract In principle, the asynchronous measurement-device-independent quantum key distribution (AMDI-QKD) can surpass the key rate capacity without phase tracking and phase locking. However, practical imperfections in sources or detections would dramatically depress its performance. Here, we present an improved model on AMDI-QKD to reduce the influence of these imperfections, including intensity fluctuation, the afterpulse effect, and the dead time of detectors. Furthermore, we carry out corresponding numerical simulations. Simulation results show that, by implementing our present work, it can have more than 100 km longer secure transmission distance and one order of magnitude enhancement in the key generation rate after 320 km compared with the standard method. Moreover, our model can still break the Pirandola–Laurenza–Ottaviani–Banchi (PLOB) bound even under realistic experimental conditions.
Secure key rate (SKR) of point-point quantum key distribution (QKD) is fundamentally bounded by the rate-loss limit. Recent breakthrough of twin-field (TF) QKD can overcome this limit and enables long distance quantum communication, but its implementation necessitates complex global phase tracking and requires strong phase references that not only add to noise but also reduce the duty cycle for quantum transmission. Here, we resolve these shortcomings, and importantly achieve even higher SKRs than TF-QKD, via implementing an innovative but simpler measurement-device-independent QKD that realizes repeaterlike communication through asynchronous coincidence pairing. Over 413 and 508 km optical fibers, we achieve finite-size SKRs of 590.61 and 42.64 bit/s, which are respectively 1.80 and 4.08 times of their corresponding absolute rate limits. Significantly, the SKR at 306 km exceeds 5 kbit/s and meets the bitrate requirement for live one-time-pad encryption of voice communication. Our work will bring forward economical and efficient intercity quantum-secure networks.
In theory, quantum key distribution (QKD) promises unconditional secure generation of the key between two remote participants, based on the laws of quantum physics. However, because of the imperfections in the real-life implementation of QKD, this promise fails. To fill the gap between the theory and implementation of QKD, different protocols have been proposed. One of them is measurement device independent (MDI) QKD, which can be implemented using present-day technology and generates a reasonable key rate. The protocol works perfectly fine for intracity communication. However, the transmission distance is not enough, so that it can replace intercity communication. For that, adaptive measurement device-independent (AMDI) QKD has been proposed. So, the present-day classical communication network such as the internet can be replaced with its quantum version. Till the date, AMDI-QKD has been implemented with threshold detectors. In this paper, we replaced threshold detectors with photon-number resolving detectors, thus making the protocol more realistic. We calculated the secret key rate for the case and discussed its dependence on transmission distance. We also discussed the dependence of the sifted key rate and quantum bit error rate (QBER) on the transmission distance.
In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication parties. Despite their advantageous performance over long communication distances, the requirement of phase locking between two remote lasers is technically challenging. By adopting the recently proposed mode-pairing idea, we realize high-performance quantum key distribution without global phase locking. Using two independent off-the-shelf lasers, we show a quadratic key-rate improvement over the conventional measurement-device-independent schemes in the regime of metropolitan and intercity distances. For longer distances, we also boost the key rate performance by 3 orders of magnitude via 304 km commercial fiber and 407 km ultralow-loss fiber. We expect this ready-to-implement high-performance scheme to be widely used in future intercity quantum communication networks.
Abstract The idea of post-measurement coincidence pairing simplifies substantially long-distance, repeater-like quantum key distribution (QKD) by eliminating the need for tracking the differential phase of the users’ lasers. However, optical frequency tracking remains necessary and can become a severe burden in future deployment of multi-node quantum networks. Here, we resolve this problem by referencing each user’s laser to an absolute frequency standard and demonstrate a practical post-measurement pairing QKD with excellent long-term stability. We confirm the setup’s repeater-like behavior and achieve a finite-size secure key rate (SKR) of 15.94 bit s−1 over 504 km fiber, which overcomes the absolute repeaterless bound by 1.28 times. Over a fiber length 100 km, the setup delivers an impressive SKR of 285.68 kbit s−1. Our work paves the way towards an efficient muti-user quantum network with the local frequency standard.