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We discuss a quantum key distribution scheme in which small phase and amplitude modulations of CW light beams carry the key information. The presence of EPR type correlations provides the quantum protection. We identify universal…

Quantum Physics · Physics 2009-11-06 T. C. Ralph

This paper proposes a new protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than…

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

Quantum key distribution allows two parties, traditionally known as Alice and Bob, to establish a secure random cryptographic key if, firstly, they have access to a quantum communication channel, and secondly, they can exchange classical…

Quantum Physics · Physics 2007-05-23 Matthias Christandl , Renato Renner , Artur Ekert

We suggest a quantum cryptographic scheme using continuous EPR-like correlations of bright optical beams. For binary key encoding, the continuous information is discretized in a novel way by associating a respective measurement, amplitude…

Quantum Physics · Physics 2009-11-07 Ch. Silberhorn , N. Korolkova , G. Leuchs

Secure quantum key distribution with multimode Gaussian entangled states and multimode homodyne detectors is proposed. In general the multimode character of both the sources of entanglement and the homodyne detectors can cause a security…

Quantum Physics · Physics 2014-12-19 Vladyslav C. Usenko , Laszlo Ruppert , Radim Filip

A cryptographic algorithm is proposed based on fully quantum mechanical keys and ciphers. Encryption and decryption are carried out via an appropriate measurement process on entangled states as governed by a quantum mechanical, asymmetrical…

Quantum Physics · Physics 2007-05-23 Guihua Zeng , Carlos Saavedra , Christoph H. Keitel

Quantum cryptography has been recently extended to continuous variable systems, e.g., the bosonic modes of the electromagnetic field. In particular, several cryptographic protocols have been proposed and experimentally implemented using…

Quantum Physics · Physics 2008-12-03 Stefano Pirandola , Stefano Mancini , Seth Lloyd , Samuel L. Braunstein

We address the security of continuous-variable quantum key distribution with squeezed states upon realistic conditions of noisy and lossy environment and limited reconciliation efficiency. Considering the generalized preparation scheme and…

Quantum Physics · Physics 2011-11-10 Vladyslav C. Usenko , Radim Filip

Mutually unbiased bases have been extensively studied in the literature and are simple and effective in quantum key distribution protocols, but they are not optimal. Here equiangular spherical codes are introduced as a more efficient and…

Quantum Physics · Physics 2016-02-23 Joseph M. Renes

An entanglement witness approach to quantum coherent state key distribution and a system for its practical implementation are described. In this approach, eavesdropping can be detected by a change in sign of either of two witness functions,…

Quantum Physics · Physics 2015-06-16 David S. Simon , Gregg Jaeger , Alexander V. Sergienko

In Gaussian quantum key distribution eavesdropping attacks are conventionally modeled through the universal entangling cloner scheme, which is based on the premise that the whole environment is under control of the adversary, i.e., the…

Quantum Physics · Physics 2020-03-04 Spyros Tserkis , Nedasadat Hosseinidehaj , Nathan Walk , Timothy C. Ralph

We propose the continuous-variable quantum key distribution protocol based on the Gaussian modulation of a single quadrature of the coherent states of light, which is aimed to provide simplified implementation compared to the symmetrically…

Quantum Physics · Physics 2016-01-12 Vladyslav C. Usenko , Frédéric Grosshans

We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e. quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while…

Quantum Physics · Physics 2009-11-07 Nicolas J. Cerf , Mohamed Bourennane , Anders Karlsson , Nicolas Gisin

Quantum key distribution (QKD) promises secure key agreement by using quantum mechanical systems. We argue that QKD will be an important part of future cryptographic infrastructures. It can provide long-term confidentiality for encrypted…

Quantum Physics · Physics 2010-01-25 Douglas Stebila , Michele Mosca , Norbert Lütkenhaus

We present here an information theoretic study of Gaussian collective attacks on the continuous variable key distribution protocols based on Gaussian modulation of coherent states. These attacks, overlooked in previous security studies,…

Quantum Physics · Physics 2009-11-10 Frederic Grosshans

A quantum key distribution protocol based on quantum encryption is presented in this Brief Report. In this protocol, the previously shared Einstein-Podolsky-Rosen pairs act as the quantum key to encode and decode the classical cryptography…

Quantum Physics · Physics 2009-11-06 Yong-Sheng Zhang , Chuan-Feng Li , Guang-Can Guo

Quantum secret-sharing protocols involving N partners (NQSS) are key distribution protocols in which Alice encodes her key into $N-1$ qubits, in such a way that all the other partners must cooperate in order to retrieve the key. On these…

Quantum Physics · Physics 2009-11-07 Valerio Scarani , Nicolas Gisin

Here we concerned with quantum key distribution - a way to establish common cryptographic key between several parties. The work proposes a combination between quantum key distribution and systematic polar coding (an error correction…

Quantum Physics · Physics 2025-11-25 Georgi Bebrov

There has been much interest in quantum key distribution. Experimentally, quantum key distribution over 150 km of commercial Telecom fibers has been successfully performed. The crucial issue in quantum key distribution is its security.…

Quantum Physics · Physics 2009-11-10 Hoi-Kwong Lo , Xiongfeng Ma , Kai Chen