Photon detection device, reception device, quantum key distribution system, and method for detecting quantum signal

A reception device comprising a photon detection device configured to detect a quantum signal, wherein:

• the photon detection device includes:
• a single photon detector that outputs a current signal indicating a result of detecting the quantum signal;
• a current-voltage convertor that converts the current signal into a voltage signal;
• an analog-to-digital converter that outputs signal obtained by analog-to-digital conversion of the voltage signal;
• and
• a signal processor that performs predetermined signal processing on the output signal, and output a detection signal indicating the result of detecting the quantum signal, and
• when a time difference between a timing at which the current signal is output from the single photon detector and a reference timing determined based on a clock signal is not within a determination range, the detection signal is not output from the signal processor.

A method for detecting a quantum signal, the method comprising:

• outputting, by a single photon detector, a current signal indicating a result of detecting the quantum signal;
• converting, by a current-voltage convertor, the current signal into a voltage signal;
• outputting, by an analog-to-digital converter, an output signal obtained by analog-to-digital conversion of the voltage signal;
• and
• performing, by a signal processor, predetermined signal processing on the output signal, and outputting a detection signal indicating the result of detecting the quantum signal,
• wherein when a time difference between a timing at which the current signal is output from the single photon detector and a reference timing determined based on a clock signal is not within a determination range, the detection signal is not output by the signal processor.