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The security of quantum key distribution (QKD) can easily be obscured if the eavesdropper can utilize technical imperfections of the actual implementation. Here we describe and experimentally demonstrate a very simple but highly effective…

We consider a generalisation of Ekert's entanglement-based quantum cryptographic protocol where qubits are replaced by qu$N$its (i.e., N-dimensional systems). In order to study its robustness against optimal incoherent attacks, we derive…

Quantum Physics · Physics 2009-11-10 Thomas Durt , Dagomir Kaszlikowski , Jing-Ling Chen , L. C. Kwek

A quantum key distribution protocol based on entanglement swapping is proposed. Through choosing particles by twos from the sequence and performing Bell measurements, two communicators can detect eavesdropping and obtain the secure key.…

Quantum Physics · Physics 2007-05-23 Fei Gao , Fenzhuo Guo , Qiaoyan Wen , Fuchen Zhu

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

By carrying out measurements on entangled states, two parties can generate a secret key which is secure not only against an eavesdropper bound by the laws of quantum mechanics, but also against a hypothetical "post-quantum" eavesdroppers…

Quantum Physics · Physics 2007-10-22 Antonio Acin , Serge Massar , Stefano Pironio

We provide a new way to bound the security of quantum key distribution using only two high-level, diagrammatic features of quantum processes: the compositional behavior of complementary measurements and the essential uniqueness of…

Quantum Physics · Physics 2017-07-20 Aleks Kissinger , Sean Tull , Bas Westerbaan

The security of a cryptographic key that is generated by communication through a noisy quantum channel relies on the ability to distill a shorter secure key sequence from a longer insecure one. We show that -- for protocols that use quantum…

Quantum Physics · Physics 2015-06-26 Dagomir Kaszlikowski , Jenn Yang Lim , Leong Chuang Kwek , Berthold-Georg Englert

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

The goal of quantum key distribution (QKD) is to establish a secure key between two parties connected by an insecure quantum channel. To use a QKD protocol in practice, one has to prove that a finite size key is secure against general…

Quantum Physics · Physics 2023-11-21 Tony Metger , Renato Renner

We discuss quantum key distribution protocols using quantum continuous variables. We show that such protocols can be made secure against individual gaussian attacks regardless the transmission of the optical line between Alice and Bob. This…

Quantum Physics · Physics 2016-09-08 F. Grosshans , N. J. Cerf , J. Wenger , R. Tualle-Brouri , Ph. Grangier

This paper demonstrates and proves that the coordination of actions in a distributed swarm can be enhanced by using quantum entanglement. In particular, we focus on - Global and local simultaneous random walks, using entangled qubits that…

Quantum Physics · Physics 2022-10-20 Yotam Ashkenazi , Shlomi Dolev

In this paper, we show that there are instances where eavesdropping causes noise reduction for a quantum key distribution (QKD) protocol. To witness these phenomena, we investigate a fault-tolerant six-state QKD protocol over a collective…

Quantum Physics · Physics 2023-07-18 Hiroo Azuma

We propose several methods for quantum key distribution (QKD) based upon the generation and transmission of random distributions of coherent or squeezed states, and we show that they are are secure against individual eavesdropping attacks.…

Quantum Physics · Physics 2016-09-08 Frédéric Grosshans , Philippe Grangier

We propose an efficient quantum key distribution scheme based on entanglement. The sender chooses pairs of photons in one of the two equivalent nonmaximally entangled states randomly, and sends a sequence of photons from each pair to the…

Quantum Physics · Physics 2009-11-07 Peng Xue , Chuan-Feng Li , Guang-Can Guo

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

In this paper, we propose an algorithm that targets contamination and eavesdropping adversaries. We consider the case when the number of independent packets available to the eavesdropper is less than the multicast capacity of the network.…

Cryptography and Security · Computer Science 2008-05-16 Yejun Zhou , Hui Li , Jianfeng Ma

The unconditional security of continuous-variable quantum key distribution is established for all schemes based on the estimation of the channel loss and excess noise. It is proved that, in the limit of large keys, Gaussian attacks are…

Quantum Physics · Physics 2010-12-15 Anthony Leverrier , Evgueni Karpov , Philippe Grangier , Nicolas J. Cerf

We analyze a cryptographic protocol for generating a distributed secret key from correlations that violate a Bell inequality by a sufficient amount, and prove its security against eavesdroppers, constrained only by the assumption that any…

Quantum Physics · Physics 2014-12-02 Ll. Masanes , R. Renner , M. Christandl , A. Winter , J. Barrett

Quantum cryptographic protocols are typically analysed by assuming that potential opponents can carry out all physical operations, an assumption which grants capabilities far in excess of present technology. Adjusting this assumption to…

Quantum Physics · Physics 2019-05-27 Nedasadat Hosseinidehaj , Nathan Walk , Timothy C. Ralph

In realistic continuous variable quantum key distribution protocols, an eavesdropper may exploit the additional Gaussian noise generated during transmission to mask her presence. We present a theoretical framework for a post-selection based…