Method for performing quantum secure direct communication in quantum communication system, and apparatus therefor

Abstract

The present specification provides a quantum secure direct communication (QSDC) method by which a transmitting end transmits a message on the basis of differential time coding, in a quantum communication system. More specifically, the method comprises the steps of: receiving, from a receiving end on a quantum channel, (i) at least one initial time state configured by including a time interval equal to a dead time of a single photon detector of the receiving end and (ii) at least one initial phase state; receiving, from the receiving end on a classical channel, time state location information for selecting a specific initial time state for encoding of information transmitted to the receiving end; selecting the specific initial time state for the encoding, on the basis of the time state location information: generating an encoding time state by encoding the information on the basis of the selected specific initial time state, the encoding time state being generated by applying a time shift on the basis of a value of the information being encoded; and transmitting a message including the encoding time state to the receiving end through the quantum channel, wherein the message is restored on the basis of a time difference between information on the at least one initial time state stored in the receiving end and information on the encoding time state.