Sending-or-Not-Sending Twin-Field Quantum Key Distribution with Redundant Space

TL;DR

This paper introduces a method using redundant space, like polarization modes, in Twin-Field QKD to reduce errors and enhance performance, especially with fewer pulses, by post-selecting events based on additional observations.

Contribution

The paper presents a novel approach incorporating redundant space in TF-QKD to improve error rates and practical performance, particularly in low-pulse scenarios.

Findings

Redundant space reduces bit-flip error rate in TF-QKD.

Method improves key rate performance with fewer pulses.

Post-selection based on additional observations enhances security.

Abstract

We propose to adopt redundant space such as polarization mode in the sending-or-not-sending Twin-Field quantum key distribution (TF-QKD) in the Fock space. With the help of redundant space such as photon polarization, we can post-select events according to the outcome of the observation to the additional quantity. This compresses the bit-flip error rate in the post-selected events of the SNS protocol. The calculation shows that the method using redundant space can greatly improve the performance in practical TF-QKD, especially when the total number of pulses is small.