Security of quantum key distribution with state-dependent imperfections

TL;DR

This paper analyzes the security of quantum key distribution systems considering practical state-dependent imperfections, providing a new approach to estimate the upper bound of phase error rates without relying on the standard GLLP formula.

Contribution

It introduces a method to assess QKD security with state-dependent imperfections, extending security analysis beyond unitary assumptions.

Findings

Security bounds for QKD with state-dependent imperfections derived

Upper bound of phase error rate estimated for practical scenarios

Analysis applicable when imperfections are not modeled as unitary transformations

Abstract

In practical quantum key distribution (QKD) system, the state preparation and measurement are imperfect comparing with the ideal BB84 protocol, which are always state-dependent in practical realizations. If the state-dependent imperfections can not be regarded as an unitary transformation, it should not be considered as part of quantum channel noise introduced by the eavesdropper, the commonly used secret key rate formula GLLP can not be applied correspondingly. In this paper, the unconditional security of quantum key distribution with state-dependent imperfection has been analyzed by estimating the upper bound of the phase error rate about the quantum channel.