Method and apparatus for performing quantum secure direct communication by using high-dimensional quantum state based on polarization and phase information in communication system

A method performed by a second device in a communication system, the method comprising:

• receiving, to a first device, a random access (RA) preamble;
• transmitting, to the second device, an RA response (RAR) message;
• establishing a channel with the first device, the channel comprising a classic channel;
• transmitting a forward pulse including photons in an initial quantum state from the first device;
• and
• receiving a backward pulse representing a plurality of bits per photon by performing phase modulation and polarization modulation on the photons based on assistance of the classic channel.

A first device in a communication system, the first device comprising:

• a transceiver;
• and
• a processor connected to the transceiver,
• wherein the processor is configured to;
• transmit, to a second device, a random access (RA) preamble;
• receive, from the second device, an RA response (RAR) message;
• establish a channel with the second device, the channel comprising a classic channel;
• receive a forward pulse including photons in an initial quantum state from the second device;
• and
• transmit a backward pulse representing a plurality of bits per photon by performing phase modulation and polarization modulation on the photons based on assistance of the classic channel.