Pan Dong, Liu Yu-Chen, Niu Penghao, Zhang Haoran, Zhang Feihao, Wang Min, Song Xiao-Tian, Chen Xiuwei, Zheng Chao, Long Gui-Lu
Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China.
Sci Adv. 2025 Feb 21;11(8):eadt4627. doi: 10.1126/sciadv.adt4627.
Quantum communication realizes information-theoretic security using photonic quantum states, for example, quantum secure direct communication (QSDC), which can achieve secure and reliable communication in a channel with both noise and eavesdroppers. However, QSDC suffers from large losses and short communication distances, thus being impractical for applications. Here, we have proposed a one-way quasi-QSDC protocol with single photons. This protocol enables the simultaneous transmission of information and key exchange using the same single photons and is robust against loss and error because it uses error correction and spectrum expansion techniques. In a proof-of-principle demonstration using weak coherent pulses, the system achieved a real-time secure transmission rate of 2.38 kilobits per second over a 104.8-kilometer standard telecommunication fiber, which set world records in both aspects. This system paved the way for the practical application of QSDC and offers a unique method to detect eavesdropping online, which is crucial in certain circumstances.
量子通信利用光子量子态实现信息理论安全，例如量子安全直接通信（QSDC），它能够在存在噪声和窃听者的信道中实现安全可靠的通信。然而，量子安全直接通信存在损耗大、通信距离短的问题，因此在实际应用中并不实用。在此，我们提出了一种基于单光子的单向准量子安全直接通信协议。该协议能够利用同一单光子同时传输信息和进行密钥交换，并且由于采用了纠错和频谱扩展技术，对损耗和错误具有鲁棒性。在使用弱相干脉冲的原理验证演示中，该系统在104.8公里的标准电信光纤上实现了每秒2.38千比特的实时安全传输速率，在这两个方面均创造了世界纪录。该系统为量子安全直接通信的实际应用铺平了道路，并提供了一种在在线检测窃听的独特方法，这在某些情况下至关重要。
