Quantum Cryptography Modulating the Spontaneous Emission Rate of Photons
Hideaki Matsueda, Fumiaki Shibata, Chikako Uchiyama · Institutional Repositories DataBase (IRDB) · 1997
A novel method of quantuIn cryptography is proposed, together with a mathemat- ical theory on the basis of nonequilibrium statistical mechanics.The proposed method involves the controlled randomness in the spontaneous emission of photons.Uncertainties in spontaneous photon emission, beam-splitting, and superposition improve the crypto- graphic security.A quantum communication channel is mathematically equivalent to a model of spin relax- ation when the Schwinger bosons are introduced.Effects of quantum mechanical devices on the propagating signals are expressed as rotation operators in the spin coherent state representation.Effect of an eavesdropper is represented by a phase shifter.The concept of"controlled randomness" is introduced to construct quantum cryptographic systems.This could be implemented by using microcavities with which the rate of spontaneous emission is controlled.In theory, this controlled randomness is analyzed with the use of the Kubo-Anderson model of spin relaxation.