Decoy States and Two Way Quantum Key Distribution Schemes

TL;DR

This paper explores applying decoy state methods to enhance the distance of two-way quantum key distribution schemes, deriving bounds and comparing practical and ideal implementations.

Contribution

It introduces two approaches for decoy state application in two-way QKD and compares them with ideal and original schemes.

Findings

Derived lower bounds on gains for practical decoy implementations

Compared two approaches with ideal infinite decoy state case

Demonstrated potential for extended QKD distance

Abstract

We study the possible application of the decoy state method on a basic two way quantum key distribution (QKD) scheme to extend its distance. Noting the obvious advantage of such a QKD scheme in allowing for single as well as double photon contributions, we derive relevant lower-bounds on the corresponding gains in a practical decoy state implementation using two intensities for decoy states. We work with two different approaches in this vein and compare these with an ideal infinite decoy state case as well as the simulation of the original.