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We propose a simplified measurement scheme for a Gaussian modulated coherent state (GMCS) protocol for continuous variable quantum key distribution (CV-QKD), utilizing homodyne detection without quadrature switching. The reference frame of…

Quantum Physics · Physics 2025-11-13 Vinod N. Rao , Emma Tien Hwai Medlock , Timothy Spiller , Rupesh Kumar

Quantum key distribution (QKD) allows two distant parties to share secret keys with the proven security even in the presence of an eavesdropper with unbounded computational power. Recently, GHz-clock decoy QKD systems have been realized by…

We present a finite-size security proof for generic quantum key distribution protocols against independent and identically distributed collective attacks and extend it to coherent attacks using the postselection technique. This work…

Quantum Physics · Physics 2025-02-11 Lars Kamin , Devashish Tupkary , Norbert Lütkenhaus

Advances in highly sensitive detection techniques for classical coherent communication systems have reduced the received signal power requirements to a few photons per bit. At this level one can take advantage of the quantum noise to create…

Quantum Physics · Physics 2019-07-23 Rupesh Kumar , Adrian Wonfor , Richard Penty , Tim Spiller , Ian White

Parameter estimation is a critical step in continuous-variable quantum key distribution (CV-QKD), especially in the finite-size regime where worst-case confidence intervals can significantly reduce the achievable secret-key rate. We provide…

The four-state continuous-variable quantum key distribution (CVQKD) protocol has a long practical secure distance \cite{Leverrier_PRL_2009}, while it has the difficulty of parameter estimation. We propose an improved four-state protocol,…

Quantum Physics · Physics 2015-06-04 Jian Yang , Bingjie Xu , Xiang Peng , Hong Guo

The security of quantum key distribution (QKD) is severely threatened by discrepancies between realistic devices and theoretical assumptions. Recently, a significant framework called the reference technique was proposed to provide security…

Quantum Physics · Physics 2022-11-21 Jie Gu , Xiao-Yu Cao , Yao Fu , Zong-Wu He , Ze-Jie Yin , Hua-Lei Yin , Zeng-Bing Chen

Measurement-device-independent quantum key distribution protocol, whose security analysis does not rely on any assumption on the detection system, can immune the attacking against detectors. We give a first composable security analysis for…

Quantum Physics · Physics 2018-09-05 Ziyang Chen , Yi-Chen Zhang , Gan Wang , Zhengyu Li , Hong Guo

We analyze the security against collective attacks for a homodyne-based continuous-variable quantum key distribution protocol using binary coherent states and postselection. We derive a lower bound of the secret key rate in an asymptotic…

Quantum Physics · Physics 2022-12-05 Ryo Namiki

Distributing secret keys with information-theoretic security is arguably one of the most important achievements of the field of quantum information processing and communications. The rapid progress in this field has enabled quantum key…

Continuous-variable quantum key distribution (CVQKD) enables remote users to share high-rate and unconditionally secure secret keys while maintaining compatibility with classical optical communication networks and effective resistance…

A continuous variable (CV), measurement device independent (MDI) quantum key distribution (QKD) protocol is analyzed, enabling three parties to connect for quantum conferencing. We utilise a generalised Bell detection at an untrusted relay…

Quantum Physics · Physics 2022-10-19 Alasdair I. Fletcher , Stefano Pirandola

Quantum cryptographic protocols are typically analysed by assuming that potential opponents can carry out all physical operations, an assumption which grants capabilities far in excess of present technology. Adjusting this assumption to…

Quantum Physics · Physics 2019-05-27 Nedasadat Hosseinidehaj , Nathan Walk , Timothy C. Ralph

Discretely-modulated continuous-variable quantum key distribution (CVQKD) is more suitable for long-distance transmission compared with its Gaussian-modulated CVQKD counterpart. However, its security can only be guaranteed when modulation…

Quantum Physics · Physics 2020-01-22 Qin Liao , Hai Zhong , Ying Guo

We propose several methods for quantum key distribution (QKD) based upon the generation and transmission of random distributions of coherent or squeezed states, and we show that they are are secure against individual eavesdropping attacks.…

Quantum Physics · Physics 2016-09-08 Frédéric Grosshans , Philippe Grangier

The optical phase shifter that constantly rotates the local oscillator phase is a necessity in continuous-variable quantum key distribution systems with heterodyne detection. In previous experimental implementations, the optical phase…

Quantum Physics · Physics 2021-09-29 Tao Shen , Yundi Huang , Xiangyu Wang , Huiping Tian , Ziyang Chen , Song Yu

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…

Measurement-device-independent quantum key distribution (MDI-QKD) can resist all attacks on the detection devices, but there are still some security issues related to the source side. One possible solution is to use the passive protocol to…

This thesis is concerned with rigorous security analyses of practical Quantum Key Distribution (QKD) protocols, using a variety of modern proof techniques. The main results are as follows. First, we establish a security proof for…

Quantum Physics · Physics 2026-04-24 Devashish Tupkary

Quantum key distribution (QKD) promises information-theoretic security based on quantum mechanics and idealized device models. Practical implementations, however, deviate from these models due to unavoidable device imperfections, and…

Quantum Physics · Physics 2026-05-14 Álvaro Navarrete , Guillermo Currás-Lorenzo , Margarida Pereira , Marcos Curty