Quantum key distribution system, optical transmitter, optical modulation control circuit, and optical modulation control method

摘要

In a quantum cryptographic transmitter (11), a phase modulator (1103, 1104) and an LN intensity modulator (1105) apply optical phase modulation and light intensity modulation to an optical signal based on desired data to generate a desired optical signal to be transmitted to a quantum cryptographic receiver (13). Based on the number of photons detected from the desired optical signal, a bias control circuit (1108) controls an operating point in light intensity modulation of the LN intensity modulator (1105).