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Quantum physics allows for unconditionally secure communication through insecure communication channels. The achievable rates of quantum-secured communication are fundamentally limited by the laws of quantum physics and in particular by the…

Quantum Physics · Physics 2015-12-16 Cosmo Lupo , Seth Lloyd

The length of a secure link over which a quantum key can be distributed depends on the efficiency and dark-count rate of the detectors used at the receiver. We report on the first demonstration of quantum key distribution using…

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

Quantum key distribution using weak coherent states and homodyne detection is a promising candidate for practical quantum-cryptographic implementations due to its compatibility with existing telecom equipment and high detection…

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 present a continuous-variable quantum key distribution protocol combining a discrete modulation and reverse reconciliation. This protocol is proven unconditionally secure and allows the distribution of secret keys over long distances,…

Quantum Physics · Physics 2010-03-15 Anthony Leverrier , Philippe Grangier

A continuous key distribution scheme is proposed that relies on a pair of canonically conjugate quantum variables. It allows two remote parties to share a secret Gaussian key by encoding it into one of the two quadrature components of a…

Quantum Physics · Physics 2009-11-06 N. J. Cerf , M. Levy , G. Van Assche

We propose a quantum repeater for continuous variable (CV) quantum optical states. Our repeater relies on an error correction protocol for loss on CV states based on CV teleportation and entanglement distillation via noiseless linear…

Quantum Physics · Physics 2015-05-15 Josephine Dias , Tim Ralph

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

The maximum distance of quantum communication is limited due to the photon loss and detector noise. Exploiting entanglement swapping, quantum relay could offer ways to extend the achievable distance by increasing the signal to noise ratio.…

Quantum Physics · Physics 2007-05-23 An-Ning Zhang , Yu-Ao Chen , Chao-Yang Lu , Xiao-Qi Zhou , Zhi Zhao , Qiang Zhang , Tao Yang , Jian-Wei Pan

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

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

Continuous-variable quantum key distribution which can be implemented using only low-cost and off-the-shelf components reveals great potential in the practical large-scale realization. Access network as a modern network necessity, connects…

Quantum Physics · Physics 2023-06-28 Xiangyu Wang , Ziyang Chen , Zhenghua Li , Dengke Qi , Song Yu , Hong Guo

Continuous-variable (CV) codes and their application in quantum communication have attracted increasing attention. In particular, one typical CV codes, cat-codes, has already been experimentally created using trapped atoms in cavities with…

Quantum Physics · Physics 2025-07-08 Pei-Zhe Li , William J. Munro , Kae Nemoto , Nicoló Lo Piparo

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

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

Long-distance quantum communication requires quantum repeaters to overcome photon loss in optical fibers. Here we demonstrate a repeater node with two memory atoms in an optical cavity. Both atoms are individually and repeatedly entangled…

Quantum Physics · Physics 2021-06-30 S. Langenfeld , P. Thomas , O. Morin , G. Rempe

The security proofs of continuous-variable quantum key distribution are based on the assumptions that the eavesdropper can neither act on the local oscillator nor control Bob's beam splitter. These assumptions may be invalid in practice due…

A feasible route towards implementing long-distance quantum key distribution (QKD) systems relies on probabilistic schemes for entanglement distribution and swapping as proposed in the work of Duan, Lukin, Cirac, and Zoller (DLCZ) [Nature…

Quantum Physics · Physics 2015-03-17 Jeyran Amirloo , Mohsen Razavi , A. Hamed Majedi

A universal deterministic noiseless quantum amplifier has been shown to be impossible. However, probabilistic noiseless amplification of a certain set of states is physically permissible. Regarding quantum state amplification as quantum…

Quantum Physics · Physics 2015-09-02 M. J. Hu , Y. S. Zhang