A practical leap towards secure quantum communication over long distances

Álvaro Cuevas, Gonzalo Carvacho, Gabriel Saavedra +7 more

Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need of a straight line between the communicating parties. The violation of Bell’s inequality offers a method for the certification of quantum links without knowing the inner workings of the devices. Energy-time entanglement quantum communication satisfies all these requirements. However, currently there is a fundamental obstacle with the standard configuration adopted: an intrinsic geometrical loophole that can be exploited to break the security of the communication, in addition to other loopholes. Here we show the first experimental Bell violation with energy-time entanglement distributed over 1 km of optical fibres that is free of this geometrical loophole. This is achieved by adopting a new experimental design, and by using an actively stabilized fibre-based long interferometer. Our results represent an important step towards long-distance secure quantum communication in optical fibres. Practical implementations of quantum communication need to securely deliver information over long distances without line-of-sight. Towards this goal, Cuevas et al.use an actively stabilized interferometer to close the geometry loophole for a Bell inequality violation over 1 km of optical fibre.

Hans J. Briegel

Nicoló Lo Piparo

Shi‐Hai Sun, Gui‐Lu Long

Deterministic secure quantum communication (DSQC) can transmit ciphered message with information theoretical security, in which the message is directly modulated on the quantum state and transmitted from Alice to Bob. Thus, key is not pre-shared, but rather communicated after the security of the ciphered message transmission is assured. In most of previous DSQC protocols, quantum memory or entanglement is necessary, which is still a big challenge with current technology. And the imperfections of practical devices, such as loss, weak coherent source, and so on, may also down play the security and efficiency of these DSQC protocols. In this article, a DSQC protocol with practical devices is proposed. In our protocol, both quantum memory and entanglement are not require. And DSQC with distance as long as 100–200 km and repetition as high as is possible.

Eleni Diamanti

Yew Kee Wong, Yifan Zhou, Zi Yan Li +2 more

Software security is crucial to ensuring the confidentiality, integrity, and availability of software systems and applications. However, conventional cryptographic methods based on mathematical assumptions are vulnerable to various attacks, especially in the era of quantum computing. Therefore, there is a need for a new paradigm of software security that can resist quantum threats. This paper proposes a novel approach to using Long-Distance Free-Space Quantum Secure Direct Communication (LF QSDC) to enhance software security. LF QSDC is a quantum communication protocol that enables two parties to exchange secret messages directly without relying on a pre-shared key or quantum error correction. Our research delves into integrating LF QSDC into software security, emphasizing its practicality for long-distance communication through the use of memory DL04 protocol, Machine Learning Enhanced JEEC, and PAT Technologies. By adopting this approach, we reinforce security for global software security and ensure their sustainability in an era where both quantum and advanced classical threats coexist side by side. Thus, LF QSDC emerges as a future-proof security mechanism highly applicable to software security systems.