Practical high-dimensional quantum key distribution with decoy states

TL;DR

This paper demonstrates practical implementation of high-dimensional quantum key distribution using one or two decoy states, achieving secure communication over long distances with high rates.

Contribution

It introduces feasible protocols for HD-QKD with limited decoy states, matching the performance of ideal protocols under realistic conditions.

Findings

HD-QKD with two decoy states can operate over 200 km distances.

Two decoy states yield secure bits per coincidence comparable to infinite decoy states.

One decoy state protocol is nearly as secure as two at short distances.

Abstract

High-dimensional quantum key distribution (HD-QKD) allows two parties to generate multiple secure bits of information per detected photon. In this work, we show that decoy state protocols can be practically implemented for HD-QKD using only one or two decoy states. HD-QKD with two decoy states, under realistic experimental constraints, can generate multiple secure bits per coincidence at distances over 200 km and at rates similar to those achieved by a protocol with infinite decoy states. Furthermore, HD-QKD with only one decoy state is practical at short distances, where it is almost as secure as a protocol with two decoy states. HD-QKD with only one or two decoy states can therefore be implemented to optimize the rate of secure quantum communications.