Heralded single photon sources for QKD applications

TL;DR

This paper evaluates the performance of heralded single photon sources in quantum key distribution, comparing symmetric and asymmetric schemes and analyzing achievable key rates with practical considerations.

Contribution

It provides a comparative analysis of symmetric and asymmetric heralded SPS schemes in QKD, including practical implementation aspects and decoy state techniques.

Findings

Symmetric and asymmetric schemes show different key rate performances.

Decoy state techniques improve security and key rates.

Passive post-selection schemes are feasible for practical QKD.

Abstract

Single photon sources (SPS) are a fundamental building block for optical implementations of quantum information protocols. Among SPSs, multiple crystal heralded single photon sources seem to give the best compromise between high pair production rate and low multiple photon events. In this work, we study their performance in a practical quantum key distribution experiment, by evaluating the achievable key rates. The analysis focuses on the two different schemes, symmetric and asymmetric, proposed for the practical implementation of heralded single photon sources, with attention on the performance of their composing elements. The analysis is based on the protocol proposed by Bennett and Brassard in 1984 and on its improvement exploiting decoy state technique. Finally, a simple way of exploiting the post-selection mechanism for a passive, one decoy state scheme is evaluated.