Finite-key analysis of a practical decoy-state high-dimensional quantum key distribution

TL;DR

This paper presents a finite-key security analysis for a practical high-dimensional decoy-state quantum key distribution protocol using time-energy entanglement, improving bounds on secure key rates and aiding practical optimization.

Contribution

It introduces a finite-key security analysis for high-dimensional decoy-state QKD, providing tighter bounds and methods for parameter optimization in practical setups.

Findings

Tighter bounds on secure-key capacity with finite-key effects

Numerical evaluation of finite-key impact under various conditions

Method for optimizing parameters in high-dimensional QKD implementations

Abstract

Compared with two-level quantum key distribution (QKD), highdimensional QKD enable two distant parties to share a secret key at a higher rate. We provide a finite-key security analysis for the recently proposed practical highdimensional decoy-state QKD protocol based on time-energy entanglement. We employ two methods to estimate the statistical fluctuation of the postselection probability and give a tighter bound on the secure-key capacity. By numerical evaluation, we show the finite-key effect on the secure-key capacity in different conditions. Moreover, our approach could be used to optimize parameters in practical implementations of highdimensional QKD.