Long-distance quantum communication through any number of entanglement swapping operations

TL;DR

This paper presents a comprehensive theoretical model for long-distance quantum communication using multiple entanglement swapping steps, accounting for realistic experimental imperfections and calculating the maximum achievable distances for secure quantum communication.

Contribution

It introduces a new mathematical framework for analyzing quantum communication over multiple entanglement swaps under realistic conditions, extending previous models.

Findings

Model supports up to three entanglement swaps

Calculates quantum communication distances exceeding Bell-inequality threshold

Incorporates realistic experimental parameters such as detector efficiency and losses

Abstract

We develop a theory and accompanying mathematical model for quantum communication via any number of intermediate entanglement swapping operations and solve numerically for up to three intermediate entanglement swapping operations. Our model yields two-photon interference visibilities post-selected on photon counts at the intermediate entanglement-swapping stations. Realistic experimental conditions are accommodated through parametric down-conversion rate, photon-counter efficiencies and dark-count rates, and instrument and transmission losses. We calculate achievable quantum communication distances such that two-photon interference visibility exceeds the Bell-inequality threshold.