Experimental realization of an orthogonal-state-encoding quantum cryptography system driven by broadband quantum memory
Phys. Rev. A 114, 022439 – Published 19 August, 2026
DOI: https://doi.org/10.1103/zh3y-95j9
Abstract
Building scalable quantum networks relies on the core device of quantum memory. Most quantum cryptography protocols utilize nonorthogonal state encoding, inevitably causing efficiency loss due to mismatch of base vectors. The orthogonal state encoding protocol, proposed by Goldenberg and Vaidman [Phys. Rev. Lett. 75, 1239 (1995)], can overcome such drawbacks by traveling the two localized wave packets of orthogonal state assisted with quantum memory. However, most existing quantum memories, limited by intrinsic storage mechanisms, cannot simultaneously meet several key indicators required for quantum communication, including high bandwidth, high efficiency, and high fidelity. Here, we developed an on-demand ultrahigh bandwidth quantum memory, reaching 95.2% storage efficiency while retaining 98.2% single-photon interference visibility. Furthermore, we experimentally integrate it with an orthogonal state encoding quantum cryptography system, demonstrating its potential to outperform the conventional BB84 quantum key distribution. This work represents an experimental implementation of an orthogonal state encoding quantum cryptography system based on quantum memory, and lays the foundation for the future realization of long-distance quantum networks.
