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

Quantum Technology: Driving Commercialisation of an Enabling Science

Secure quantum communications beyond the repeaterless secret key capacity

Marco Lucamarini

Published Oct 6, 2021• 0 citations
Publisher

Abstract

Since they were first introduced, quantum communications have evolved into a mature technology that is making its way to market. Quantum key distribution (QKD), in particular, allows the exchange of information with security that stems from the very laws of quantum mechanics and hence is not impaired by future technological advances. These same laws, however, restrict the QKD transmission range, as they forbid a straightforward amplification of quantum signals. This leads to a fundamental rate-distance bound known as the “repeaterless secret key capacity” (SKC0), which was thought to be impossible to overcome without a full-fledged quantum repeater. The recent proposal of “Twin-Field QKD” challenged this belief and showed how to overcome the SKC0 with an effective quantum repeater, realisable with present-day technology. This allows to perform QKD over long-distance and high-loss channels. In my talk, I will review the main concepts and most significant results behind this novel idea.

DOI
10.1117/12.2601566

Related papers

Quantum key distribution beyond the repeaterless rate-loss limit (Conference Presentation)

Marco Lucamarini, Mirko Pittaluga, Mariella Minder +4 more

Quantum key distribution (QKD) allows users to generate shared encryption keys that are guaranteed to be theoretically secure by the laws of quantum mechanics. Most implementations use light pulses that are attenuated by the propagation medium. This leads to a fundamental rate-distance limit in QKD that was thought to be impossible to overcome with current technology. The recent proposal of "Twin-Field QKD", however, changed this belief and showed how to overcome this limit and perform long-distance QKD with present-day technology. In my talk I will review the most significant theoretical and experimental results in this emerging and rapidly growing research area.

•Mar 10, 2020•0 citations

Quantum key distribution beyond the repeaterless secret key capacity

Mariella Minder

Quantum communications promise to provide information theoretic security in the exchange of information. However, unlike their classical counterpart, they utilise dim optical pulses whose amplification is prohibited. Consequently, their transmission rate and range is confined below a theoretical limit known as repeaterless secret key capacity. Overcoming this limit with today’s technology was believed to be impossible until the recent proposal of Twin-field (TF) quantum key distribution (QKD), a scheme that uses phase-coherent optical signals and an auxiliary measuring station to distribute quantum information. Here, TF-QKD and its main variations are initially explored and compared in simulations, to assess their performance in different attributes. Such schemes are also practically implemented for the first time in two experiments. The first is a proof-of-principle implementation over significant channel losses, in excess of 90 dB. In the second, the setup is developed further and the protocol is implemented over real fibre channels exceeding 600 km in length, representing the first fibre-based secure quantum communication beyond the barriers of 600 km and 100 dB. In both cases, in the high loss/distance regime, the resulting secure key rates exceed the repeaterless secret key capacity, a result never achieved before.

•Aug 24, 2020•0 citations

Information theoretic security of quantum key distribution overcoming the repeaterless secret key capacity bound

Kiyoshi Tamaki, Hoi‐Kwong Lo, Wenyuan Wang +1 more

Quantum key distribution is a way to distribute secret keys to distant users with information theoretic security and key rates suitable for real-world applications. Its rate-distance figure, however, is limited by the natural loss of the communication channel and can never surpass a theoretical limit known as point-to-point secret key capacity. Recently, a new type of quantum key distribution with an intermediate relay was proposed to overcome this limit (M. Lucamarini, Z. L. Yuan, J. F. Dynes and A. J. Shields, Nature, 2018). However, a standard application of the decoy state method limited the security analysis of this scheme to hold under restrictive assumptions for the eavesdropper. Hence, overcoming the point-to-point secret key capacity with an information-theoretic secure scheme is still an open question. Here, we propose a novel way to use decoy states to answer this question. The key idea is to switch between a Test mode and a Code mode, the former enabling the decoy state parameter estimation and the latter generating a key through a phase encoding protocol. This way, we confirm the scaling properties of the original scheme and overcome the secret key capacity at long distances. Our work plays a key role to unlock the potential of practical secure quantum communications.

arXiv:1805.05511•May 15, 2018•39 citations

Overcoming the private capacity of optical point-to-point quantum key distribution

Koji Azuma

The private capacity of a lossy bosonic channel shows that there remains not much room to improve known point-to-point quantum key distribution (QKD) protocols further, in terms of the key rate versus distance. The current question in our field is how to overcome this fundamental limit with the help of a single station in the middle between communicators. In this talk, we explore recent trials to achieve this goal, such as adaptive measurement-device-independent QKD and twin-field QKD. These trials are good milestones towards the realization of quantum repeater networks.

Quantum Communications and Quantum Imaging•Jul 30, 2021•0 citations

Long-Distance Secure Communication Based on Quantum Repeater Deployment with Quantum-Key Distribution

S. Baskar, Michaelraj Kingston Roberts, K.P. Sridhar

Long-distance communication data cannot be safely sent over the Internet without strong key distribution mechanisms and long-term, secure communication routes. In recent days, distributing a secret key across faraway entities connected by an optical fibre or open space has been the goal of quantum key distribution. The previous quantum method challenge in guaranteeing the integrity of qubits makes long-distance communication a challenging endeavour. With a growing number of cyber dangers, it is more important than ever to guarantee safe interaction. Quantum computers can easily crack traditional key exchange techniques, which create shared secret keys for protection. A quantum key distributionbased secure communication model (QKD-SCM) has been suggested for large-scale networks to rapidly ascertain the bare minimum of quantum repeaters needed to provide end-to-end connections among all end hosts. The suggested QKD-SCM evaluates the safety and efficiency of existing point-to-point QKD systems. The QKD-SCM with Quantum repeaters setup breaks the channel into quantum memory (QM), which is climbable and allows for long-distance quantum communication. The end of the channel is used to produce entangled qubits. Experiments show that QKD-SCM can succeed in making long-distance networks very secure with less communication delay.

International Conference on Artificial Intelligence for Internet of Things (AIIoT)•May 3, 2024•4 citations

A Study on Quantum Key Distribution Satellite Communications

Filip Lauterbach, Michal Vanëk, Miralem Mehić +1 more

Quantum key distribution (QKD) is a secure communication technique which uses quantum mechanics to protect communications. To overcome large distances, it requires the use of quantum repeaters, which are still challenging nevertheless feasible, or Twin-Field-QKD (TF-QKD) technology, which has been demonstrated several years ago. As it develops and matures, quantum technology is expected to play an increasingly major role in networks. Satellite QKD enables secure communication between devices via both satellites and ground stations. The study explores the transmission of quantum encryption technology in space and presents an overview of cubesats and satellites that currently use quantum key distribution (QKD) technology.

International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT)•Oct 30, 2023•5 citations
Since they were first introduced, quantum communications have evolved into a mature technology that is making its way to market. Quantum key distribution (QKD), in particular, allows the exchange of information with security that stems from the very laws of quantum mechanics and hence is not impaired by future technological advances. These same laws, however, restrict the QKD transmission range, as they forbid a straightforward amplification of quantum signals. This leads to a fundamental rate-distance bound known as the “repeaterless secret key capacity” (SKC0), which was thought to be impossible to overcome without a full-fledged quantum repeater. The recent proposal of “Twin-Field QKD” challenged this belief and showed how to overcome the SKC0 with an effective quantum repeater, realisable with present-day technology. This allows to perform QKD over long-distance and high-loss channels. In my talk, I will review the main concepts and most significant results behind this novel idea.
Quantum key distribution (QKD) allows users to generate shared encryption keys that are guaranteed to be theoretically secure by the laws of quantum mechanics. Most implementations use light pulses that are attenuated by the propagation medium. This leads to a fundamental rate-distance limit in QKD that was thought to be impossible to overcome with current technology. The recent proposal of "Twin-Field QKD", however, changed this belief and showed how to overcome this limit and perform long-distance QKD with present-day technology. In my talk I will review the most significant theoretical and experimental results in this emerging and rapidly growing research area.
Quantum communications promise to provide information theoretic security in the exchange of information. However, unlike their classical counterpart, they utilise dim optical pulses whose amplification is prohibited. Consequently, their transmission rate and range is confined below a theoretical limit known as repeaterless secret key capacity. Overcoming this limit with today’s technology was believed to be impossible until the recent proposal of Twin-field (TF) quantum key distribution (QKD), a scheme that uses phase-coherent optical signals and an auxiliary measuring station to distribute quantum information. Here, TF-QKD and its main variations are initially explored and compared in simulations, to assess their performance in different attributes. Such schemes are also practically implemented for the first time in two experiments. The first is a proof-of-principle implementation over significant channel losses, in excess of 90 dB. In the second, the setup is developed further and the protocol is implemented over real fibre channels exceeding 600 km in length, representing the first fibre-based secure quantum communication beyond the barriers of 600 km and 100 dB. In both cases, in the high loss/distance regime, the resulting secure key rates exceed the repeaterless secret key capacity, a result never achieved before.
Quantum key distribution is a way to distribute secret keys to distant users with information theoretic security and key rates suitable for real-world applications. Its rate-distance figure, however, is limited by the natural loss of the communication channel and can never surpass a theoretical limit known as point-to-point secret key capacity. Recently, a new type of quantum key distribution with an intermediate relay was proposed to overcome this limit (M. Lucamarini, Z. L. Yuan, J. F. Dynes and A. J. Shields, Nature, 2018). However, a standard application of the decoy state method limited the security analysis of this scheme to hold under restrictive assumptions for the eavesdropper. Hence, overcoming the point-to-point secret key capacity with an information-theoretic secure scheme is still an open question. Here, we propose a novel way to use decoy states to answer this question. The key idea is to switch between a Test mode and a Code mode, the former enabling the decoy state parameter estimation and the latter generating a key through a phase encoding protocol. This way, we confirm the scaling properties of the original scheme and overcome the secret key capacity at long distances. Our work plays a key role to unlock the potential of practical secure quantum communications.
The private capacity of a lossy bosonic channel shows that there remains not much room to improve known point-to-point quantum key distribution (QKD) protocols further, in terms of the key rate versus distance. The current question in our field is how to overcome this fundamental limit with the help of a single station in the middle between communicators. In this talk, we explore recent trials to achieve this goal, such as adaptive measurement-device-independent QKD and twin-field QKD. These trials are good milestones towards the realization of quantum repeater networks.
Long-distance communication data cannot be safely sent over the Internet without strong key distribution mechanisms and long-term, secure communication routes. In recent days, distributing a secret key across faraway entities connected by an optical fibre or open space has been the goal of quantum key distribution. The previous quantum method challenge in guaranteeing the integrity of qubits makes long-distance communication a challenging endeavour. With a growing number of cyber dangers, it is more important than ever to guarantee safe interaction. Quantum computers can easily crack traditional key exchange techniques, which create shared secret keys for protection. A quantum key distributionbased secure communication model (QKD-SCM) has been suggested for large-scale networks to rapidly ascertain the bare minimum of quantum repeaters needed to provide end-to-end connections among all end hosts. The suggested QKD-SCM evaluates the safety and efficiency of existing point-to-point QKD systems. The QKD-SCM with Quantum repeaters setup breaks the channel into quantum memory (QM), which is climbable and allows for long-distance quantum communication. The end of the channel is used to produce entangled qubits. Experiments show that QKD-SCM can succeed in making long-distance networks very secure with less communication delay.
Quantum key distribution (QKD) is a secure communication technique which uses quantum mechanics to protect communications. To overcome large distances, it requires the use of quantum repeaters, which are still challenging nevertheless feasible, or Twin-Field-QKD (TF-QKD) technology, which has been demonstrated several years ago. As it develops and matures, quantum technology is expected to play an increasingly major role in networks. Satellite QKD enables secure communication between devices via both satellites and ground stations. The study explores the transmission of quantum encryption technology in space and presents an overview of cubesats and satellites that currently use quantum key distribution (QKD) technology.