Limiting rate of secret-key generation in quantum cryptography in spacetime
S. N. Molotkov · Journal of Experimental and Theoretical Physics Letters · 2002
The fundamental restrictions on the maximum admissible rate of secret-key commitment in quantum cryptography in real time are discussed. It is shown that the maximum rate in a quantum channel with limited transmission band is achieved in a cryptosystem on orthogonal states. The dimensionless rate (the number of bits per unit time frequency band through unit of the channel) is determined by the universal function C (λ 0 (Δ kT ))/Δ kT [where C (λ 0 (Δ kT )) is the transmission capacity of a classical binary channel, Δ k is the transmission band width, 1/ T is the transmission frequency of quantum states, and λ 0 is the maximum eigenvalue of a certain integral equation].