Abstract: A quantum key distribution method according to the present invention includes an error probability estimation step of estimating error probabilities of transmission data and the received data, an error correcting step of correcting errors in the received data based on error correcting information, a matching determination step of determining whether the transmission data and the received data after correcting errors match, and an information amount estimating step of estimating an amount of information leaked to an adversary through a quantum communication path, and further compresses data based on the amount of information made public in a process of processing via a public communication path and an estimated value of the amount of information leaked to the adversary through the quantum communication path to make the data after compression a cryptographic key shaped by devices.

Abstract: A transmitter sets a time length, determines a time point at which phases of frequency signals coincide within a range of the time length, defines a determined time point as a time reference point, aligns the phases of the frequency signals based on the time reference point, combines phase-aligned frequency, and transmits combined frequency signals to a receiver by the time length as the communication signals. The receiver receives the communication signals, extracts the phases of the frequency signals, obtains a time point at which the phases coincide, and determines an obtained time point as the time reference point.