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

Annales de Physique

Quantum key distribution over 25 km using a fibre set-up based on continuous variables

Jérôme Lodewyck, Matthieu R. Bloch, Simon Fossier, Eleni Diamanti, Thierry Debuisschert, Rosa Tualle-Brouri, Philippe Grangier

Published Jan 1, 2007• 0 citations
Publisher

Abstract

We describe a continuous variable quantum key distribution set-up allowing for secret key rates over 2 kbits/s on a 25 km fibre link. The signal and the phase reference are time-multiplexed in the same fibre. The system is designed to be operated on an installed fibre link. The reconciliation step is performed using fast and efficient LDPC error correcting codes.

DOI
10.1051/anphys:2008033

Related papers

Quantum key distribution over 25 km with an all-fiber continuous-variable system

Jérôme Lodewyck, Matthieu R. Bloch, Raúl García−Patrón +8 more

We report on the implementation of a reverse-reconciliated coherent-state continuous-variable quantum key distribution system, with which we generated secret keys at a rate of more than $2\phantom{\rule{0.3em}{0ex}}\mathrm{kb}∕\mathrm{s}$ over $25\phantom{\rule{0.3em}{0ex}}\mathrm{km}$ of optical fiber. Time multiplexing is used to transmit both the signal and phase reference in the same optical fiber. Our system includes all experimental aspects required for a field implementation of a quantum key distribution setup. Real-time reverse reconciliation is achieved by using fast and efficient low-density parity check error correcting codes.

arXiv:0706.4255•Physical Review A•Oct 3, 2007•542 citations

Field test of a continuous-variable quantum key distribution prototype

Simon Fossier, Eleni Diamanti, Thierry Debuisschert +3 more

We have designed and realized a prototype that implements a continuous-variable quantum key distribution (QKD) protocol based on coherent states and reverse reconciliation. The system uses time and polarization multiplexing for optimal transmission and detection of the signal and phase reference, and employs sophisticated error-correction codes for reconciliation. The security of the system is guaranteed against general coherent eavesdropping attacks. The performance of the prototype was tested over preinstalled optical fibres as part of a quantum cryptography network combining different QKD technologies. The stable and automatic operation of the prototype over 57 h yielded an average secret key distribution rate of 8 kbit s −1 over a 3 dB loss optical fibre, including the key extraction process and all quantum and classical communication. This system is therefore ideal for securing communications in metropolitan size networks with high-speed requirements.

arXiv:0812.3292•New Journal of Physics•Apr 30, 2009•217 citations

High spectral efficiency digital coherent continuous variable quantum key distribution system using polarization-multiplexed QPSK reference signal

T. Kawakami, K. Yoshino, Wakako Maeda +1 more

We designed a digital coherent continuous variable quantum key distribution system achieving higher spectral efficiency by extracting timing information from a polarization-multiplexed QPSK reference signal and demonstrated the feasibility of distributing a secret key over a 100 km SMF link.

IET conference proceedings.•Nov 13, 2023•0 citations

Short Blocklength Error Correction Codes for Continuous-Variable Quantum Key Distribution

Kadir Gümüş, João Frazão, Boris Škorić +4 more

We introduce a two-step error correction scheme for reconciliation in continuous-variable quantum key distribution systems. Using this scheme, it is possible to use error correction codes with small blocklengths (1000 bits), increasing secret key rates at a distance of 140km by up to 7.3 times.

arXiv:2507.03529•European Conference on Optical Communication•Sep 28, 2025•0 citations

Experimental demonstration of continuous-variable quantum key distribution over 80 km of standard telecom fiber

Paul Jouguet, Sébastien Kunz-Jacques, Anthony Leverrier +2 more

Summary form only given. Continuous-variable quantum key distribution (CVQKD) is a promising alternative to commonly used discrete-variable QKD protocols, because this technology can be implemented with standard telecom components and recent results suggest that it will be compatible with standard wavelength division multiplexed telecommunication networks [1]. Security proofs against general eavesdropping attacks are available for CVQKD protocols using Gaussian modulation [2], and field implementations over deployed telecommunication networks have been demonstrated over the past few years [3].Long-distance operation of CVQKD systems, however, has been hindered until now by the limited efficiency of the complex error-correction (or reconciliation) algorithms that are required to extract the secret key from the correlated data shared by Alice and Bob. We have designed high-efficiency error correcting-codes [4] allowing to extract an errorless secret key in a CVQKD protocol using a Gaussian modulation of coherent states and a homodyne detection system. These codes are available for a wide range of signal-to-noise ratios on a Gaussian noise channel with a binary modulation and can be combined with a multidimensional reconciliation method [5]. This improved reconciliation procedure considerably extends the secure range of a continuous-variable quantum key distribution with Gaussian modulation.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•May 1, 2013•8 citations

Continuous-variable QKD over 50 km commercial fiber

Yichen Zhang, Zhengyu Li, Ziyang Chen +18 more

Abstract The continuous-variable version of quantum key distribution (QKD) offers the advantages (over discrete-variable systems) of higher secret key rates in metropolitan areas, as well as the use of standard telecom components that can operate at room temperature. An important step in the real-world adoption of continuous-variable QKD is the deployment of field tests over commercial fibers. Here we report two different field tests of a continuous-variable QKD system through commercial fiber networks in Xi’an and Guangzhou over distances of 30.02 km (12.48 dB) and 49.85 km (11.62 dB), respectively. We achieve secure key rates two orders-of-magnitude higher than previous field test demonstrations by employing an efficient calibration model with one-time evaluation. This accomplishment is also realized by developing a fully automatic control system which stabilizes system noise, and by applying a rate-adaptive reconciliation method which maintains high reconciliation efficiency with high success probability in fluctuated environments. Our results pave the way for the deployment of continuous-variable QKD in metropolitan settings.

arXiv:1709.04618•Quantum Science and Technology•May 29, 2019•222 citations
We describe a continuous variable quantum key distribution set-up allowing for secret key rates over 2 kbits/s on a 25 km fibre link. The signal and the phase reference are time-multiplexed in the same fibre. The system is designed to be operated on an installed fibre link. The reconciliation step is performed using fast and efficient LDPC error correcting codes.
We report on the implementation of a reverse-reconciliated coherent-state continuous-variable quantum key distribution system, with which we generated secret keys at a rate of more than 2kb∕s2\phantom{\rule{0.3em}{0ex}}\mathrm{kb}∕\mathrm{s}2kb∕s over 25km25\phantom{\rule{0.3em}{0ex}}\mathrm{km}25km of optical fiber. Time multiplexing is used to transmit both the signal and phase reference in the same optical fiber. Our system includes all experimental aspects required for a field implementation of a quantum key distribution setup. Real-time reverse reconciliation is achieved by using fast and efficient low-density parity check error correcting codes.
We have designed and realized a prototype that implements a continuous-variable quantum key distribution (QKD) protocol based on coherent states and reverse reconciliation. The system uses time and polarization multiplexing for optimal transmission and detection of the signal and phase reference, and employs sophisticated error-correction codes for reconciliation. The security of the system is guaranteed against general coherent eavesdropping attacks. The performance of the prototype was tested over preinstalled optical fibres as part of a quantum cryptography network combining different QKD technologies. The stable and automatic operation of the prototype over 57 h yielded an average secret key distribution rate of 8 kbit s −1 over a 3 dB loss optical fibre, including the key extraction process and all quantum and classical communication. This system is therefore ideal for securing communications in metropolitan size networks with high-speed requirements.
Summary form only given. Continuous-variable quantum key distribution (CVQKD) is a promising alternative to commonly used discrete-variable QKD protocols, because this technology can be implemented with standard telecom components and recent results suggest that it will be compatible with standard wavelength division multiplexed telecommunication networks [1]. Security proofs against general eavesdropping attacks are available for CVQKD protocols using Gaussian modulation [2], and field implementations over deployed telecommunication networks have been demonstrated over the past few years [3].Long-distance operation of CVQKD systems, however, has been hindered until now by the limited efficiency of the complex error-correction (or reconciliation) algorithms that are required to extract the secret key from the correlated data shared by Alice and Bob. We have designed high-efficiency error correcting-codes [4] allowing to extract an errorless secret key in a CVQKD protocol using a Gaussian modulation of coherent states and a homodyne detection system. These codes are available for a wide range of signal-to-noise ratios on a Gaussian noise channel with a binary modulation and can be combined with a multidimensional reconciliation method [5]. This improved reconciliation procedure considerably extends the secure range of a continuous-variable quantum key distribution with Gaussian modulation.
Abstract The continuous-variable version of quantum key distribution (QKD) offers the advantages (over discrete-variable systems) of higher secret key rates in metropolitan areas, as well as the use of standard telecom components that can operate at room temperature. An important step in the real-world adoption of continuous-variable QKD is the deployment of field tests over commercial fibers. Here we report two different field tests of a continuous-variable QKD system through commercial fiber networks in Xi’an and Guangzhou over distances of 30.02 km (12.48 dB) and 49.85 km (11.62 dB), respectively. We achieve secure key rates two orders-of-magnitude higher than previous field test demonstrations by employing an efficient calibration model with one-time evaluation. This accomplishment is also realized by developing a fully automatic control system which stabilizes system noise, and by applying a rate-adaptive reconciliation method which maintains high reconciliation efficiency with high success probability in fluctuated environments. Our results pave the way for the deployment of continuous-variable QKD in metropolitan settings.