Quantum key distribution system and operation method thereof

A method of operating a quantum key distribution system based on an RFI (reference frame independent) QKD (quantum key distribution) protocol, the method comprising:

• transmitting and receiving a quantum signal through a quantum channel based on transmission basis information, transmission bit information, reception basis information, and reception bit information;
• obtaining pair of bases information including first base pair information including polarization state information for a first base pair and second base pair information including polarization state information for a plurality of second base pairs, the pair of bases information being composed of a combination of the transmission basis information and the reception basis information;
• obtaining quantum bit error rate (QBER) information based on the pair of bases information;
• measuring a plurality of security parameters based on the pair of bases information;
• measuring a first security parameter associated with all of the plurality of second pairs of bases and a second security parameter associated with some of the plurality of second pairs of bases, based on the second pair of bases information;
• loading a pre-stored maximum value of a third security parameter;
• correcting a bit error of the reception bit information based on the QBER information;
• and
• generating a secret key based on the plurality of security parameters,
• wherein the third security parameter is calculated based on the first security parameter and the second security parameter.

A method of operating a quantum key distribution system based on an RFI (reference frame independent) QKD (quantum key distribution) protocol, the method comprising:

• setting a plurality of misaligned angles;
• transmitting and receiving a quantum signal based on transmission basis information, transmission bit information, reception basis information, and reception bit information, with respect to each of the plurality of misaligned angles;
• measuring a first security parameter and a second security parameter based on the transmission basis information and the reception basis information;
• measuring a plurality of third security parameters corresponding to the plurality of misaligned angles based on the first security parameter and the second security parameter;
• and
• measuring a maximum value of the plurality of third security parameters and storing the maximum value, and
• wherein each of the plurality of misaligned angles is an angle between a reference axis of a transmitting device and a reference axis of a receiving device.