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We analyse a central broadcast continuous variable quantum key distribution protocol in which a beam produced by a thermal source is used to create a secret key between two parties, Alice and Bob. A beam splitter divides the initial beam…

Quantum Physics · Physics 2021-10-12 Adam Walton , Anne Ghesquière , George Brumpton , David Jennings , Ben Varcoe

Li et al. presented a protocol [Int. Journal of Quantum Information, Vol. 4, No. 6 (2006) 899-906] for quantum key distribution based on entanglement swapping. In this protocol they use random and certain bits to construct a classical key…

Quantum Physics · Physics 2008-05-29 Stefan Schauer , Martin Suda

This paper discusses the use of computer-aided verification as a practical means for analysing quantum information systems; specifically, the BB84 protocol for quantum key distribution is examined using this method. This protocol has been…

Cryptography and Security · Computer Science 2007-05-23 Rajagopal Nagarajan , Nikolaos Papanikolaou , Garry Bowen , Simon Gay

Several simple yet secure protocols to authenticate the quantum channel of various QKD schemes, by coupling the photon sender's knowledge of a shared secret and the QBER Bob observes, are presented. It is shown that Alice can encrypt…

Quantum Physics · Physics 2007-05-23 J. T. Kosloski

We present a method for determining the presence of an eavesdropper in QKD systems without using any public bit comparison. Alice and Bob use a duplex QKD channel and the bit transport technique for relays. The only information made public…

Quantum Physics · Physics 2012-03-06 Stephen M. Barnett , Simon J. D. Phoenix

Since the invention of Bennett-Brassard 1984 (BB84) protocol, many quantum key distribution (QKD) protocols have been proposed and some protocols are operated even in field environments. One of the striking features of QKD is that QKD…

Quantum Physics · Physics 2016-01-18 Hiroki Takesue , Toshihiko Sasaki , Kiyoshi Tamaki , Masato Koashi

The ability to distribute secret keys between two parties with information-theoretic security, that is, regardless of the capacities of a malevolent eavesdropper, is one of the most celebrated results in the field of quantum information…

Quantum Physics · Physics 2015-09-01 Eleni Diamanti , Anthony Leverrier

We consider the extraction of shared secret key from correlations that are generated by either a classical or quantum source. In the classical setting, two honest parties (Alice and Bob) use public discussion and local randomness to distill…

Quantum Physics · Physics 2015-10-27 Eric Chitambar , Benjamin Fortescue , Min-Hsiu Hsieh

The security of quantum key distribution protocols hinges upon features of physical systems that are uniquely quantum in nature. We explore the role of quantumness as qualified by quantum contextuality, in quantum key distribution schemes.…

Quantum Physics · Physics 2017-07-04 Jaskaran Singh , Kishor Bharti , Arvind

A central assumption in quantum key distribution (QKD) is that Eve has no knowledge about which rounds will be used for parameter estimation or key distillation. Here we show that this assumption is violated for iterative sifting, a sifting…

Quantum Physics · Physics 2016-05-12 Corsin Pfister , Norbert Lütkenhaus , Stephanie Wehner , Patrick J. Coles

Standard quantum key distribution protocols are provably secure against eavesdropping attacks, if quantum theory is correct. It is theoretically interesting to know if we need to assume the validity of quantum theory to prove the security…

Quantum Physics · Physics 2009-11-10 Jonathan Barrett , Lucien Hardy , Adrian Kent

In device-independent quantum key distribution (DIQKD), an adversary prepares a device consisting of two components, distributed to Alice and Bob, who use the device to generate a secure key. The security of existing DIQKD schemes holds…

Quantum Physics · Physics 2022-08-01 Tony Metger , Yfke Dulek , Andrea Coladangelo , Rotem Arnon-Friedman

Quantum key distribution (QKD) systems can send signals over more than 100 km standard optical fiber and are widely believed to be secure. Here, we show experimentally for the first time a technologically feasible attack, namely the…

Quantum Physics · Physics 2011-04-05 Yi Zhao , Chi-Hang Fred Fung , Bing Qi , Christine Chen , Hoi-Kwong Lo

We propose a quantum key distribution scheme by using screening angles and analyzing detectors which enable to notice the presence of Eve who eavesdrops the quantum channel, as the revised protocol of the recent quantum key distribution…

Quantum Physics · Physics 2007-05-23 Won-Ho Kye

This paper introduces two information-theoretically secure protocols that achieve quantum secure direct communication between Alice and Bob in the first case, and among Alice, Bod and Charlie in the second case. Both protocols use the same…

Quantum Physics · Physics 2025-03-14 Theodore Andronikos , Alla Sirokofskich

The quantum key distribution protocol BB84, published by C. H. Bennett and G. Brassard in 1984, describes how two spatially separated parties can generate a random bit string fully known only to them by transmission of single-qubit quantum…

Quantum Physics · Physics 2007-12-28 Olli Ahonen

Recently, Zhang et al. proposed a single-state semi-quantum key distribution protocol (Int. J. Quantum Inf, 18, 4, 2020) to help a quantum participant to share a secret key with a classical participant. However, this study shows that an…

Quantum Physics · Physics 2020-09-29 Jun Gu , Tzonelih Hwang

We present a quantum communication protocol which keeps all the properties of the ping-pong protocol [Phys. Rev. Lett. 89, 187902 (2002)] but improves the capacity doubly as the ping-pong protocol. Alice and Bob can use the variable…

Quantum Physics · Physics 2009-11-10 Qing-yu Cai , Bai-wen Li

The security of a standard bi-directional "plug & play" quantum key distribution (QKD) system has been an open question for a long time. This is mainly because its source is equivalently controlled by an eavesdropper, which means the source…

Quantum Physics · Physics 2009-11-13 Yi Zhao , Bing Qi , Hoi-Kwong Lo

Quantum cryptography uses techniques and ideas from physics and computer science. The combination of these ideas makes the security proofs of quantum cryptography a complicated task. To prove that a quantum-cryptography protocol is secure,…

Quantum Physics · Physics 2015-05-13 Normand J. Beaudry