Quantum Key Distribution with Mismatched Measurements over Arbitrary Channels

TL;DR

This paper derives new key-rate formulas for quantum key distribution protocols that incorporate mismatched measurement data, revealing higher noise tolerance and broad applicability to arbitrary quantum channels.

Contribution

It introduces novel key-rate expressions using mismatched basis statistics, applicable to any quantum channel, and demonstrates increased noise tolerance in semi-quantum protocols.

Findings

Semi-quantum protocol tolerates noise levels comparable to BB84.

Key-rate formulas applicable to arbitrary quantum channels.

Enhanced understanding of mismatched measurement data in QKD.

Abstract

In this paper, we derive key-rate expressions for different quantum key distribution protocols. Our key-rate equations utilize multiple channel statistics, including those gathered from mismatched measurement bases - i.e., when Alice and Bob choose incompatible bases. In particular, we will consider an Extended B92 and a two-way semi-quantum protocol. For both these protocols, we demonstrate that their tolerance to noise is higher than previously thought - in fact, we will show the semi-quantum protocol can actually tolerate the same noise level as the fully quantum BB84 protocol. Along the way, we will also consider an optimal QKD protocol for various quantum channels. Finally, all the key-rate expressions which we derive in this paper are applicable to any arbitrary, not necessarily symmetric, quantum channel.