Discrete-phase-randomized measurement-device-independent quantum key distribution

TL;DR

This paper identifies vulnerabilities in measurement-device-independent quantum key distribution caused by imperfect phase randomization and proposes a discrete-phase-randomized protocol to enhance security against source-side attacks.

Contribution

It introduces a discrete-phase-randomized protocol to close source-side loopholes in measurement-device-independent quantum key distribution.

Findings

Demonstrates loopholes due to imperfect phase randomization

Proposes a discrete-phase-randomized protocol as a solution

Enhances security by closing source-side attack vulnerabilities

Abstract

Measurement-device-independent quantum key distribution removes all detector-side attacks in quantum cryptography, and in the meantime doubles the secure distance. The source side, however, is still vulnerable to various attacks. In particular, the continuous phase randomization assumption on the source side is normally not fulfilled in experimental implementation and may potentially open a loophole. In this work, we first show that indeed there are loopholes for imperfect phase randomization in measurement-device-independent quantum key distribution by providing a concrete attack. Then we propose a discrete-phase-randomized measurement-device-independent quantum key distribution protocol as a solution to close this source-side loophole.