Experimental demonstration of reference-frame-independent quantum key distribution with a free-space/fiber integrated channel
Ye Chen, Xiaodong Fan, Tianxiang Zhan +10 more
A global quantum secure network (QSN) based on quantum key distribution (QKD) has emerged as a significant trend since it provides an unconditionally secure way to defeat the threat posed by quantum computers. The nodes, based on ground or mobile platforms, are connected with two different channels, free-space and fiber. In this paper, a qubit-based synchronization reference-frame-independent (RFI) QKD is demonstrated in the field with a free-space/fiber integrated channel, in which the bright classical reference-frame calibration and clock synchronization signals are removed, and the quantum state is directly converted between two different channels without extra coding/decoding operations. It not only reduces the complexity of QKD and QSN but also enhances the practical security (e.g., removing calibration attacks and trusted repeaters). A key rate of 799.2 bps is achieved under 7 km urban free-space and 75 km fiber link. And the long time tests of a continuous 12 h without human intervention also demonstrate the stability of our system under such an integrated channel. Thus, we believe this work opens a way to implement a simple, flexible, and low-cost QSN.
Photonics Research•Jun 22, 2026•0 citations