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Continuous-variable quantum key distribution exploits coherent measurements of the electromagnetic field, i.e., homodyne or heterodyne detection. The most advanced security proofs developed so far relied on idealised mathematical models for…

Quantum Physics · Physics 2022-03-18 Cosmo Lupo , Yingkai Ouyang

Quantum conditional entropies play a fundamental role in quantum information theory. In quantum key distribution, they are exploited to obtain reliable lower bounds on the secret-key rates in the finite-size regime, against collective…

Quantum Physics · Physics 2026-03-05 Gabriele Staffieri , Giovanni Scala , Cosmo Lupo

We have designed and realized a prototype that implements a continuous-variable quantum key distribution protocol based on coherent states and reverse reconciliation. The system uses time and polarization multiplexing for optimal…

We consider discrete-modulation protocols for continuous-variable quantum key distribution (CV-QKD) that employ a modulation constellation consisting of a finite number of coherent states and that use a homodyne or a heterodyne-detection…

Quantum Physics · Physics 2021-01-20 Eneet Kaur , Saikat Guha , Mark M. Wilde

Discrete-modulated continuous-variable quantum key distribution offers a pragmatic solution, greatly simplifying experimental procedures while retaining robust integration with classical optical communication. Theoretical analyses have…

Quantum Physics · Physics 2024-07-31 Mingze Wu , Junhui Li , Bingjie Xu , Song Yu , Yichen Zhang

We establish a lower bound on the asymptotic secret key rate of continuous-variable quantum key distribution with a discrete modulation of coherent states. The bound is valid against collective attacks and is obtained by formulating the…

Quantum Physics · Physics 2019-06-27 Shouvik Ghorai , Philippe Grangier , Eleni Diamanti , Anthony Leverrier

Most continuous-variable quantum key distribution schemes are based on the Gaussian modulation of coherent states followed by continuous quadrature detection using homodyne detectors. In all previous schemes, the Gaussian modulation has…

Quantum Physics · Physics 2016-09-06 Tobias Gehring , Christian S. Jacobsen , Ulrik L. Andersen

We experimentally demonstrate adaptive reconciliation for continuous-variable quantum key distribution over a turbulent free-space optical channel. Additionally, we propose a method for optimising the reconciliation efficiency, increasing…

Recent studies showed the finite-size security of binary-modulation CV-QKD protocols against general attacks. However, they gave poor key-rate scaling against transmission distance. Here, we extend the security proof based on…

Quantum Physics · Physics 2023-08-30 Takaya Matsuura , Shinichiro Yamano , Yui Kuramochi , Toshihiko Sasaki , Masato Koashi

We address the security of continuous-variable quantum key distribution with squeezed states upon realistic conditions of noisy and lossy environment and limited reconciliation efficiency. Considering the generalized preparation scheme and…

Quantum Physics · Physics 2011-11-10 Vladyslav C. Usenko , Radim Filip

Quantum key distribution (QKD) is a quantum-proof key-exchange scheme which is fast approaching the communication industry. An essential component in QKD is the information reconciliation step, which is used for correcting the…

Quantum Physics · Physics 2019-02-26 E. O. Kiktenko , A. S. Trushechkin , C. C. W. Lim , Y. V. Kurochkin , A. K. Fedorov

Continuous variable quantum key distribution (CVQKD) with discrete modulation combines advantages of CVQKD, such as the implementability using readily available technologies, with advantages of discrete variable quantum key distribution,…

Quantum Physics · Physics 2025-02-13 Carlos Pascual-García , Stefan Bäuml , Mateus Araújo , Rotem Liss , Antonio Acín

We consider continuous-variable quantum key distribution with discrete-alphabet encodings. In particular, we study protocols where information is encoded in the phase of displaced coherent (or thermal) states, even though the results can be…

Quantum Physics · Physics 2021-01-18 Panagiotis Papanastasiou , Stefano Pirandola

We establish an analytical lower bound on the asymptotic secret key rate of continuous-variable quantum key distribution with an arbitrary modulation of coherent states. Previously, such bounds were only available for protocols with a…

Quantum Physics · Physics 2021-09-15 Aurélie Denys , Peter Brown , Anthony Leverrier

Continuous-variable quantum key distribution (CV-QKD) has been proposed as a method for securely exchanging keys to protect against the security concerns caused by potential advancements in quantum computing. In addition to optical fibre…

We present a protocol for quantum key distribution using discrete modulation of coherent states of light. Information is encoded in the variable phase of coherent states which can be chosen from a regular discrete set ranging from binary to…

Quantum Physics · Physics 2015-05-13 Denis Sych , Gerd Leuchs

We investigate the composable security of unidimensional contin- uous variable quantum key distribution (UCVQKD), which is based on the Gaussian modulation of a single quadrature of the coherent-state of light, aiming to provide a simple…

Quantum Physics · Physics 2017-08-08 Qin Liao , Ying Guo , Cailang Xie , Duang Huang , Peng Huang , Guihua Zeng

The possibility of using squeezed states in the recently suggested unidimensional continuous-variable quantum key distribution based on a single quadrature modulation is addressed. It is shown that squeezing of the signal states expands the…

Quantum Physics · Physics 2018-09-26 Vladyslav C. Usenko

Continuous-variable (CV) quantum key distribution (QKD) allows for quantum secure communication with the benefit of being close to existing classical coherent communication. In recent years, CV QKD protocols using a discrete number of…

Existing experimental implementations of continuous-variable quantum key distribution require shot-noise limited operation, achieved with shot-noise limited lasers. However, loosening this requirement on the laser source would allow for…

Quantum Physics · Physics 2016-09-22 Christian S. Jacobsen , Tobias Gehring , Ulrik L. Andersen