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Continuous-variable quantum key distribution (CVQKD) is considered to be an alternative to classical cryptography for secure communication. However, its transmission distance is restricted to metropolitan areas, given that it is affected by…

Quantum Physics · Physics 2018-12-12 Jian Zhou , Duan Huang , Ying Guo

Quantum key distribution provides secure keys resistant to code-breaking quantum computers. The continuous-variable version of quantum key distribution offers the advantages of higher secret key rates in metropolitan areas, as well as the…

Passive quantum key distribution (QKD) has been proposed for discrete variable protocols to eliminate side channels in the source. Unfortunately, the key rate of passive DV-QKD protocols suffers from sifting loss and additional quantum…

Quantum Physics · Physics 2022-12-06 Chenyang Li , Chengqiu Hu , Wenyuan Wang , Rong Wang , Hoi-Kwong Lo

We realize an end-to-end no-switching quantum key distribution protocol using continuous-wave coherent light. We encode weak broadband Gaussian modulations onto the amplitude and phase quadratures of light beams at the Shannon's information…

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

We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of fading channels. These are lossy channels whose transmissivity changes according to a probability distribution. This is…

Quantum Physics · Physics 2018-03-21 Panagiotis Papanastasiou , Christian Weedbrook , Stefano Pirandola

The original two-way continuous-variable quantum-key-distribution (CV QKD) protocols [S. Pirandola, S. Mancini, S. Lloyd, and S. L. Braunstein, Nature Physics 4, 726 (2008)] give the security against the collective attack on the condition…

Quantum Physics · Physics 2012-10-16 Maozhu Sun , Xiang Peng , Yujie Shen , Hong Guo

We propose an improved two-way continuous-variable quantum key distribution (CV QKD) protocol by adding proper random noise on the receiver's homodyne detection, the security of which is analysed against general collective attacks. The…

Quantum Physics · Physics 2013-05-07 Maozhu Sun , Xiang Peng , Hong Guo

Quantum key distribution (QKD) offers information-theoretic security based on the fundamental laws of physics. However, device imperfections, such as those in active modulators, may introduce side-channel leakage, thus compromising…

Quantum Physics · Physics 2023-05-10 Chengqiu Hu , Wenyuan Wang , Kai-Sum Chan , Zhenghan Yuan , Hoi-Kwong Lo

Quantum key distribution is one of the most fundamental cryptographic protocols. Quantum walks are important primitives for computing. In this paper we take advantage of the properties of quantum walks to design new secure quantum key…

Quantum Physics · Physics 2018-10-04 Chrysoula Vlachou , Walter Krawec , Paulo Mateus , Nikola Paunkovic , Andre Souto

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 show that covert secret key expansion is possible using a public authenticated classical channel and a quantum channel largely under control of an adversary, which we precisely define. We also prove a converse result showing that, under…

Information Theory · Computer Science 2019-11-12 Mehrdad Tahmasbi , Matthieu R. Bloch

We demonstrate, for the first time to our knowledge, continuous-variable quantum key distribution using probabilistically-shaped 1024-QAM and true local oscillator, achieving 38.3Mb/s secret key rate over 9.5km, averaged over the…

Numerical methods are widely used to calculate the secure key rate of many quantum key distribution protocols in practice, but they consume many computing resources and are too time-consuming. In this work, we take the homodyne detection…

Quantum key distribution can be enhanced and extended if nonclassical single-photon states of light are used. We study a connection between the security of quantum key distribution and quantum non-Gaussianity of light arriving at the…

Quantum Physics · Physics 2017-07-13 Mikołaj Lasota , Radim Filip , Vladyslav C. Usenko

The local oscillator in practical continuous-variable quantum key distribution system fluctuates at any time during the key distribution process, which may open security loopholes for the eavesdropper to hide her eavesdropping behaviors.…

Quantum Physics · Physics 2023-08-02 Lu Fan , Yiming Bian , Mingze Wu , Yichen Zhang , Song Yu

The continuous variable quantum key distribution has been considered to have the potential to provide high secret key rate. However, in present experimental demonstrations, the secret key can be distilled only under very small loss rates.…

Quantum Physics · Physics 2008-06-03 Yi-Bo Zhao , You-Zhen Gui , Jin-Jian Chen , Zheng-Fu Han , Guang-Can Guo

We develop a method to connect the infinite-dimensional description of optical continuous-variable quantum key distribution (QKD) protocols to a finite-dimensional formulation. The secure key rates of the optical QKD protocols can then be…

Quantum Physics · Physics 2021-05-26 Twesh Upadhyaya , Thomas van Himbeeck , Jie Lin , Norbert Lütkenhaus

Quantum key distribution (QKD) enables two remote parties to grow a shared key which they can use for unconditionally secure communication [1]. The applicable distance of a QKD protocol depends on the loss and the excess noise of the…

Quantum Physics · Physics 2012-10-08 Lars S. Madsen , Vladyslav C. Usenko , Mikael Lassen , Radim Filip , Ulrik L. Andersen

We provide security bounds against coherent attacks for two families of quantum key distribution protocols that use $d$-dimensional quantum systems. In the asymptotic regime, both the secret key rate for fixed noise and the robustness to…

Quantum Physics · Physics 2015-03-13 Lana Sheridan , Valerio Scarani