Quantum key distribution can provide unconditionally secure key exchange for remote users in theory. In practice, however, in most quantum key distribution systems, quantum hackers might steal the secure keys by listening to the side channels in the source, such as the photon frequency spectrum, emission time, propagation direction, spatial angular momentum, and so on. It is hard to prevent such kinds of attacks because side channels may exist in any of the encoding space whether the designers take care of or not. Here we report an experimental realization of a side-channel-free quantum key distribution protocol which is not only measurement-device-independent, but also immune to all side-channel attacks in the source. We achieve a secure key rate of 4.80e-7 per pulse through 50 km fiber spools.
@article{arxiv.2103.06058,
title = {Experimental Side-Channel-Free Quantum Key Distribution},
author = {Chi Zhang and Xiao-Long Hu and Jiu-Peng Chen and Yang Liu and Weijun Zhang and Zong-Wen Yu and Hao Li and Lixing You and Zhen Wang and Xiang-Bin Wang and Qiang Zhang and Jian-Wei Pan},
journal= {arXiv preprint arXiv:2103.06058},
year = {2022}
}