Measurement-device-independent one-step quantum secure direct communication

TLDR

One‑step quantum secure direct communication (QSDC) allows direct transmission of secret messages without prior key distribution. The authors propose two measurement‑device‑independent (MDI) one‑step QSDC protocols to strengthen security against imperfect measurement devices. The protocols employ identical polarization‑spatial‑mode two‑photon hyperentangled states, hyperentanglement swapping, and either nonlinear‑optical complete or linear‑optical partial hyperentanglement Bell state measurements, followed by polarization‑degree‑of‑freedom encoding and a third‑party hyperentanglement‑assisted complete polarization Bell state measurement. Both protocols are theoretically unconditionally secure, with simulations showing a maximum communication distance of about 354 km and indicating potential future applications in quantum secure communication. Published in Bulletin.

Abstract

The one-step quantum secure direct communication (QSDC) ( Sci. Bull. 67 , 367 (2022)) can effectively simplify QSDC’s operation and reduce message loss. For enhancing its security under practical experimental condition, we propose two measurement-device-independent (MDI) one-step QSDC protocols, which can resist all possible attacks from imperfect measurement devices. In both protocols, the communication parties prepare identical polarization-spatial-mode two-photon hyperentangled states and construct the hyperentanglement channel by hyperentanglement swapping. The first MDI one-step QSDC protocol adopts the nonlinear-optical complete hyperentanglement Bell state measurement (HBSM) to construct the hyperentanglement channel, while the second protocol adopts the linear-optical partial HBSM. Then, the parties encode the photons in the polarization degree of freedom and send them to the third party for the hyperentanglement-assisted complete polarization Bell state measurement. Both protocols are unconditionally secure in theory. The simulation results show the MDI one-step QSDC protocol with complete HBSM attains the maximal communication distance of about 354 km. Our MDI one-step QSDC protocols may have potential applications in the future quantum secure communication field.