Relativistic quantum key distribution system with one-way quantum communication

TL;DR

This paper introduces a relativistic quantum key distribution system that leverages causality to inherently prevent unambiguous state discrimination attacks, enhancing security in practical metropolitan line-of-sight setups.

Contribution

The authors propose a novel relativistic QKD protocol that is inherently immune to USD-based eavesdropping, simplifying security analysis and improving practical deployment.

Findings

System is practical for metropolitan line-of-sight communication

Inherently immune to USD-based attacks due to relativistic causality

Allows straightforward and comprehensive security analysis

Abstract

Unambiguous state discrimination (USD) is one of the major obstacles for practical quantum key distribution (QKD). Often overlooked, it allows efficient eavesdropping in majority of practical systems, provided the overall channel loss is above a certain threshold. Thus, to remain secure all such systems must not only monitor the actual loss, but also possess a comprehensive information on the safe 'loss vs. BER' levels, which is often well beyond currently known security analyses. The more advanced the protocol the tougher it becomes to find and prove corresponding bounds. To get out of this vicious circle and solve the problem outright, we demonstrate a so called relativistic QKD system, which uses causality to become inherently immune to USD-based attacks. The system proves to be practical in metropolitan line-of-sight arrangements. At the same time it has a very basic structure that allows for a straightforward and comprehensive security analysis.