One-step quantum secure direct communication

Yu-Bo Sheng; Lan Zhou; Gui-Lu Long

doi:10.1016/j.scib.2021.11.002

One-step quantum secure direct communication

Sci Bull (Beijing). 2022 Feb 26;67(4):367-374. doi: 10.1016/j.scib.2021.11.002. Epub 2021 Nov 4.

Authors

Yu-Bo Sheng¹, Lan Zhou², Gui-Lu Long³

Affiliations

¹ College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; Institute of Quantum Information and Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China. Electronic address: shengyb@njupt.edu.cn.
² School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210003, China.
³ Department of Physics, Tsinghua University, Beijing 100084, China; State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China; Beijing National Research Center for Information Science and Technology, Beijing 100084, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China. Electronic address: gllong@tsinghua.edu.cn.

PMID: 36546088
DOI: 10.1016/j.scib.2021.11.002

Abstract

Quantum secure direct communication (QSDC) attracts much attention for it can transmit secret messages directly without sharing a key. In this article, we propose a one-step QSDC protocol, which only requires to distribute polarization-spatial-mode hyperentanglement for one round. In this QSDC protocol, the eavesdropper cannot obtain any message, so that this protocol is unconditionally secure in principle. This protocol is a two-way quantum communication and has high capacity for it can transmit two bits of secret messages with one pair of hyperentanglement. With entanglement fidelities of both polarization and spatial-mode degrees of freedom being 0.98, the maximal communication distance of this one-step QSDC can reach about 216 km. QSDC can also be used to generate the key. In this regard, the key generation rate is estimated about 2.5 times of that in the entanglement-based QKD with the communication distance of 150 km. With the help of future quantum repeaters, this QSDC protocol can provide unconditionally secure communication over arbitrarily long distance.

Keywords: Hyperentanglement; Nonlocal Bell-state analysis; Quantum secure direct communication.