QUANTUM COMMUNICATION DEVICE, QUANTUM COMMUNICATION METHOD, AND COMPUTER PROGRAM PRODUCT

According to an embodiment, a quantum communication device includes a receiver, a sift processor, an estimator, first and second storages, a determination unit, an error corrector, a measurement unit, and a privacy amplifier. The sift processor acquires sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases. The estimator acquires an estimated error rate by estimating an error rate of the sift processing data from an error rate of part of the sift processing data. When a sift processing data volume stored in the first storage is not smaller than a first threshold, the determination unit determines order of the sift processing data to be corrected based on an estimated error rate, an error rate range that a check matrix can correct, and estimated correction time, and the check matrix used for correction.