Quantum key distribution with realistic heralded single photon sources

TL;DR

This paper evaluates the performance of four-state quantum key distribution using realistic heralded single-photon sources, considering detector noise and imperfections to determine secure key rates and distances.

Contribution

It provides a theoretical analysis incorporating realistic detector models, offering formulas and insights into optimizing quantum key distribution systems.

Findings

Heralding detector characteristics critically influence key rate and security distance.

Analytical formulas effectively predict performance, aligning with numerical results.

Imperfect detectors reduce maximum secure distance and key rate.

Abstract

We analyze theoretically performance of four-state quantum key distribution protocols implemented with a realistic heralded single-photon source. The analysis assumes a noisy model for the detector heralding generation of individual photons via spontaneous parametric down-conversion, including dark counts and imperfect photon number resolution. We identify characteristics of the heralding detector that defines the attainable cryptographic key rate and the maximum secure distance. Approximate analytical formulas are applied to multiplexed detection and compared with results of numerical calculations.