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Quantum computing poses significant threats to conventional cryptographic techniques such as RSA and AES, motivating the need for quantum secure communication methods. Quantum Key Distribution (QKD) offers information theoretic security…

Flaws in the process of modulation, or encoding of key bits in the quadratures of the electromagnetic light field, can make continuous-variable quantum key distribution systems susceptible to leakage of secret information. Here, we report…

How to remove detector side channel attacks has been a notoriously hard problem in quantum cryptography. Here, we propose a simple solution to this problem---*measurement* device independent quantum key distribution. It not only removes all…

Quantum Physics · Physics 2012-05-30 Hoi-Kwong Lo , Marcos Curty , Bing Qi

We investigate quantum key distribution (QKD) in optical multiple-input-multiple-output (MIMO) settings. Such settings can prove useful in dealing with harsh channel conditions as in, e.g., satellite-based QKD. We study a $2\times2$ setting…

Quantum Physics · Physics 2023-08-23 Shradhanjali Sahu , Ahmed Lawey , Mohsen Razavi

Quantum key distribution (QKD) offers a theoretically secure method to share secret keys, yet practical implementations face challenges due to noise and loss over long-distance channels. Traditional QKD protocols require extensive noise…

Quantum Physics · Physics 2025-08-01 Hannah Seabrook , Emilien Lavie , Teodor Strömberg , Matthew P. Stafford , Giulia Rubino

Quantum key distribution (QKD) offers an unconditionally secure means of communication based on the laws of quantum mechanics. Currently, a major challenge is to achieve a QKD system with a 40 dB channel loss, which is required if we are to…

In this paper, we show that there are instances where eavesdropping causes noise reduction for a quantum key distribution (QKD) protocol. To witness these phenomena, we investigate a fault-tolerant six-state QKD protocol over a collective…

Quantum Physics · Physics 2023-07-18 Hiroo Azuma

A semi-quantum key distribution (SQKD) protocol allows a quantum user and a limited "classical" user to establish a shared secret key secure against an all-powerful adversary. In this work, we present a new SQKD protocol where the quantum…

Quantum Physics · Physics 2017-10-17 Walter O. Krawec , Eric P. Geiss

Many papers proved the security of quantum key distribution (QKD) system, in the asymptotic framework. The degree of the security has not been discussed in the finite coding-length framework, sufficiently. However, to guarantee any…

Quantum Physics · Physics 2009-11-13 Masahito Hayashi

We address continuous variable quantum key distribution (QKD) in non-Markovian lossy channels and show how the non-Markovian features may be exploited to enhance security and/or to detect the presence and the position of an eavesdropper…

Quantum Physics · Physics 2015-05-20 Ruggero Vasile , Stefano Olivares , Matteo G A Paris , Sabrina Maniscalco

Practical implementations of Quantum Key Distribution (QKD) extending beyond urban areas commonly use satellite links. However, the transmission of quantum states through the Earth's atmosphere is highly susceptible to noise, restricting…

Quantum Physics · Physics 2025-11-20 Florian Kanitschar , Marcus Huber

Quantum key distribution (QKD) based on the laws of quantum physics allows the secure distribution of secret keys over an insecure channel. Unfortunately, imperfect implementations of QKD compromise its information-theoretical security.…

Noise causes severe difficulties in implementing quantum computing and quantum cryptography. Several schemes have been suggested to reduce this problem, mainly focusing on quantum computation. Motivated by quantum cryptography, we suggest a…

Quantum Physics · Physics 2007-05-23 T. Mor

We have developed a method to calculate a secret key rate of a continuous-variable quantum-key-distribution scheme using four coherent states and postselection for a general model of Gaussian attacks. We assume that the transmission line…

Quantum Physics · Physics 2018-10-30 Ryo Namiki , Akira Kitagawa , Takuya Hirano

We propose a long-distance continuous-variable quantum key distribution (CVQKD) with four-state protocol using non-Gaussian state-discrimination detection. A photon subtraction operation, which is deployed at the transmitter, is used for…

Quantum Physics · Physics 2018-07-23 Qin Liao , Ying Guo , Duang Huang , Peng Huang , Guihua Zeng

Numerically, a theoretical analysis of the noise impact caused by spontaneous Raman scattering, four-wave mixing, and linear channel crosstalk on the measurement-device-independent continuous variable quantum key distribution systems is…

Quantum Physics · Physics 2023-04-03 Irina Vorontsova , Roman Goncharov , Sergey Kynev , Fedor Kiselev , Vladimir Egorov

Continuous-variable quantum key distribution (CV-QKD) has many practical advantages including compatibility with current optical communication technology. Implementation using heterodyne measurements is particularly attractive since it…

Quantum Physics · Physics 2022-08-26 Shinichiro Yamano , Takaya Matsuura , Yui Kuramochi , Toshihiko Sasaki , Masato Koashi

Quantum key distribution(QKD) might be the most famous application of quantum information theory. The idea of QKD is not difficult to understand but in practical implementations, many problems are needed to be solved, for example, the noise…

Quantum Physics · Physics 2023-08-01 Hao Shu , Chang-Yue Zhang , Yue-Qiu Chen , Zhu-Jun Zheng , Shao-Ming Fei

We propose a long-distance continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) protocol with discrete modulation. This kind of discrete-modulated schemes have good compatibility with efficient error…

Quantum Physics · Physics 2019-02-22 Hong-Xin Ma , Peng Huang , Dong-Yun Bai , Tao Wang , Shi-Yu Wang , Wan-Su Bao , Gui-Hua Zeng

Establishing scalable, secure quantum networks requires advancing beyond conventional point-to-point quantum key distribution (QKD) protocols toward point-to-multipoint QKD protocols. Here, we generalize a well-established…