Mask-coding-assisted continuous-variable quantum direct communication with orbital angular momentum multiplexing

TL;DR

This paper presents a novel continuous-variable quantum secure direct communication scheme using mask-coding and orbital angular momentum multiplexing, significantly improving secrecy capacity and noise suppression for long-distance quantum communication.

Contribution

It introduces a new QSDC protocol combining mask-coding with orbital angular momentum, enhancing security and capacity over existing methods.

Findings

Bit error rate decreased by 36% to 0.38%

System excess noise measured at 0.0184 SNU

Secrecy capacity achieved is 6.319 million bps

Abstract

Quantum secure direct communication (QSDC) is a approach of communication to transmit secret messages base on quantum mechanics. Different from the quantum key distribution, secret messages can be transmitted directly on quantum channel with QSDC. Higher channel capacity and noise suppression capabilities are key to achieving long-distance quantum communication. Here we report a continuous-variable QSDC scheme based on mask-coding and orbital angular momentum, in which the mask-coding is employed to protect the security of the transmitting messages and to suppression the influence of excess noise. And the combination of orbital angular momentum and the information block transmission can effectively improve the secrecy capacity. In the 800 information blocks * 1310 bits length 10-km experiment, the results show that the statistical average of bit error rate has decreased by 36% and reached 0.38% comparing to existing solutions, and the system excess noise is 0.0184 SNU, and the final secrecy capacity is 6.319 * 106 bps. Therefore, this scheme reduces error bits while increasing secrecy capacity, providing a solution for long-distance large-scale quantum communication.