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Amplification plays a key role in classical communication protocols, where it compensates the unavoidable loss of the signal. However, when we enter the quantum domain this approach starts being problematic as the standard kinds of…

Quantum Physics · Physics 2014-07-30 Petr Marek , Radim Filip

Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require advanced experimental techniques such as noiseless amplification.…

We propose and demonstrate a fully passive discrete-state continuous-variable quantum key distribution (CV-QKD), which can eliminate all modulator side channels on the source side, using a local local oscillator (LLO). The CV-QKD system…

Quantum Physics · Physics 2026-05-04 Yu Zhang , Xuyang Wang , Chenyang Li , Jie Yun , Qiang Zeng , Zhiliang Yuan , Zhenguo Lu , Yongmin Li

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 noiseless linear amplifier (NLA) performs the highest quality amplification allowable under the rules of quantum physics. Unfortunately, these same rules conspire against us via the no-cloning theorem, which constrains NLA operations to…

Quantum Physics · Physics 2023-10-27 Joshua J. Guanzon , Matthew S. Winnel , Deepesh Singh , Austin P. Lund , Timothy C. Ralph

The noiseless amplification or attenuation are two heralded filtering operations that enable respectively to increase or decrease the mean field of any quantum state of light with no added noise, at the cost of a small success probability.…

Quantum Physics · Physics 2013-05-30 Jaromir Fiurasek , Nicolas J. Cerf

A continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol using squeezed states is proposed where the two legitimate partners send Gaussian-modulated squeezed states to an untrusted third party to…

Quantum Physics · Physics 2014-11-20 Yi-Chen Zhang , Zhengyu Li , Song Yu , Wanyi Gu , Xiang Peng , Hong Guo

Linear quantum amplifiers are indispensable tools for quantum technologies, yet their performance is fundamentally limited by quantum noise, precluding any signal-to-noise ratio (SNR) enhancement unless supplemented by post-selection or…

Quantum Physics · Physics 2026-03-13 Ya-Long Ren , Rong-Teng Cao , Sheng-Li Ma , Ren Zhang , Fu-Li Li , Franco Nori , Peng-Bo Li

The imperfections of a receiver's detector affect the performance of two-way continuous-variable quantum key distribution protocols and are difficult to adjust in practical situations. We propose a method to improve the performance of…

Quantum Physics · Physics 2014-02-24 Yi-Chen Zhang , Zhengyu Li , Christian Weedbrook , Song Yu , Wanyi Gu , Maozhu Sun , Xiang Peng , Hong Guo

We propose a novel scheme for continuous variable quantum key distribution(CV-QKD) using the subcarrier multiplexing technique which was employed in microwave photonics. This scheme allows to distribute N channels independent Gaussian…

Quantum Physics · Physics 2014-02-19 Jian Fang , Peng Huang , Guihua Zeng

The two-way capacities of quantum channels determine the ultimate entanglement and secret-key distribution rates achievable by two distant parties that are connected by a noisy transmission line, in absence of quantum repeaters. Since…

Quantum Physics · Physics 2025-01-27 Francesco Anna Mele , Ludovico Lami , Vittorio Giovannetti

Amplification of quantum states is inevitably accompanied with the introduction of noise at the output. For protocols that are probabilistic with heralded success, noiseless linear amplification in theory may still possible. When the…

Quantum Physics · Physics 2017-04-28 Syed Assad , Mark Bradshaw , Ping Koy Lam

Noise is the price to pay when trying to clone or amplify arbitrary quantum states. The quantum noise associated to linear phase-insensitive amplifiers can only be avoided by relaxing the requirement of a deterministic operation. Here we…

Quantum Physics · Physics 2015-05-18 A. Zavatta , J. Fiurásek , M. Bellini

This paper proposes a multi-mode Gaussian modulated continuous variable quantum key distribution (CV-QKD) scheme able to operate at high bandwidth despite using conventional noisy, coherent detectors. We demonstrate enhancement in shotnoise…

Quantum Physics · Physics 2019-07-24 Rupesh Kumar , Xinke Tang , Adrian Wonfor , Richard Penty , Ian White

In a continuous-variable quantum key distribution (CVQKD) system, the information is conveyed by coherent state carriers. The quantum continuous variables are sent through a quantum channel, where the presence of the eavesdropper adds a…

Quantum Physics · Physics 2015-06-17 Laszlo Gyongyosi

A continuous-variable quantum key distribution protocol based on squeezed states and heterodyne detection is introduced and shown to attain higher secret key rates over a noisy line than any other one-way Gaussian protocol. This increased…

Quantum Physics · Physics 2009-11-13 Raul Garcia-Patron , Nicolas J. Cerf

In a practical continuous-variable quantum-key distribution (CVQKD), the fluctuations of the local oscillator (LO) not only make the normalization of Bob's measurement outcomes difficult, but also can change the signal-to-noise ratio (SNR)…

Quantum Physics · Physics 2014-03-12 Xiang-Chun Ma , Shi-Hai Sun , Mu-Sheng Jiang , Ming Gui , Yan-Li Zhou , Lin-Mei Liang

The idea of signal amplification is ubiquitous in the control of physical systems, and the ultimate performance limit of amplifiers is set by quantum physics. Increasing the amplitude of an unknown quantum optical field, or more generally…

Quantum Physics · Physics 2010-06-16 G. Y. Xiang , T. C. Ralph , A. P. Lund , N. Walk , G. J. Pryde

Quantum key distribution relying on the principles of quantum mechanics enables two parties to produce a shared random secret key, thereby ensuring the security of data transmission. Continuous variable quantum key distribution (CV-QKD) is…

Quantum Physics · Physics 2025-03-05 Dengke Qi , Xiangyu Wang , Jiayu Ma , Zhenghua Li , Ziyang Chen , Yueming Lu , Song Yu

We experimentally demonstrated a sub-Mbps key rate Gaussian-modulated coherent-state continuous-variable quantum key distribution (CV-QKD) over 100 km transmission distance. To efficiently control the excess noise, the quantum signal and…

Quantum Physics · Physics 2023-04-12 Yaodi Pi , Heng Wang , Yan Pan , Yun Shao , Yang Li , Jie Yang , Yichen Zhang , Wei Huang , Bingjie Xu