| （英） |
Quantum Key Distribution (QKD) has been attracting attention as an important technique to share an information-theoretically secure key under the existence of an eavesdropper. However, a security claim has been made repeatedly since 2009 that trace distance, a security parameter in QKD, is not interpreted correctly. The interpretation states that trace distance between a distributed quantum state and an ideal quantum state gives a probability that the distributed state is not ideal. However, the interpretation may be based on misuse of coupling theorem. Therefore, this study simulated by a physical random number generator whether the probability can be given by the trace distance. The result showed that the interpretation was wrong. Thus, to evaluate the security of QKD, it is required to give a new interpretation of trace distance and the failure probability of QKD. |