QUANTUM INFORMATION SCIENCE

On the stability of fiber-optic quantum cryptography at arbitrary losses in a communication channel: Exclusion of unambiguous measurements

S. N. Molotkov<sup>abc

a</sup> Institute of Solid State Physics, Russian Academy of Sciences
^b Academy of Criptography of Russia
^c M. V. Lomonosov Moscow State University, Faculty of Computational Mathematics and Cybernetics

Abstract: Since a source of quantum states is not strictly single-photon and losses exist in a communication channel, an attack with unambiguous measurements is possible, leading to loss of security. The problem of the stability of quantum key distribution protocols in a channel with large losses is still unsolved. A radical solution of this problem has been proposed by completely excluding unambiguous measurements by an eavesdropper. The problem is solved by means of counting of classical reference pulses. The conservation of the number of classical sync pulses results in the impossibility of unambiguous measurements. In this case, losses in the communication channel are considered as a priori unknown and can vary during a series of messages.

Received: 08.08.2014

DOI: 10.7868/S0370274X1418012X

 English version: Journal of Experimental and Theoretical Physics Letters, 2014, 100:6, 413–419

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