Mismatched-basis statistics enable quantum key distribution with uncharacterized qubit sources

TL;DR

This paper introduces a novel postprocessing method that utilizes mismatched-basis measurement statistics to enable secure quantum key distribution with uncharacterized qubit sources, expanding the capabilities of existing protocols.

Contribution

It demonstrates that incorporating mismatched-basis statistics allows uncharacterized qubit sources to be used in measurement-device-independent QKD and BB84 protocols, which was previously impossible.

Findings

Enables secure QKD with uncharacterized sources

Utilizes mismatched-basis measurement data effectively

Expands the applicability of existing QKD protocols

Abstract

In the postprocessing of quantum key distribution, the raw key bits from the mismatched-basis measurements, where two parties use different bases, are normally discarded. Here, we propose a postprocessing method that exploits measurement statistics from mismatched-basis cases, and prove that incorporating these statistics enables uncharacterized qubit sources to be used in the measurement-device-independent quantum key distribution protocol and the Bennett-Brassard 1984 protocol, a case which is otherwise impossible.