Optimum Condition of Squeezed State Signal for Optical Communication with Energy Loss


IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.8   pp.775-783
Publication Date: 1988/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Communication Theory

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For the quantum state control communication, one of the most serious problems is the effect of transmission loss which degrades the advantage of the quantum state controlled signal. In this paper, we investigate loss effect for the squeezed state signal, which is one of typical quantum state controlled signals. First, it is shown that when the squeezed state signal optimized regardless of the effect of loss is used as transmitter state in the communication system with energy loss, the signal to noise ratio of the received signal is higher than that of the coherent state signal with the same transmitted photon number when and only when the loss is less than 3 dB. Then this paper gives an optimum condition of the squeezed state signal for lossy channel. This optimum condition provides higher signal to noise ratio of the received signal than that of coherent state signal for any degree of loss. Furthermore, we compare the performance of the quantum coherent communication systems using the optimum squeezed state signal with that of the photon communication using the photon number state signal taking the effect of loss into account.