Characterizing Bell state analyzer using weak coherent pulses

TL;DR

This paper proposes a practical method to characterize Bell state analyzers using weak coherent pulses, addressing errors from non-ideal inputs, and experimentally verifies its effectiveness in quantum key distribution.

Contribution

It introduces a new method to deduce BSA performance with weak coherent pulses, improving practical quantum communication implementations.

Findings

Method accurately characterizes BSA with weak coherent pulses

Experimental verification confirms feasibility in quantum key distribution

Reduces errors from non-ideal single-photon inputs

Abstract

Bell state analyzer (BSA) is one of the most crucial apparatus in photonic quantum information processing. While linear optics provide a practical way to implement BSA, it provides unavoidable errors when inputs are not ideal single-photon states. Here, we propose a simple method to deduce the BSA for single-photon inputs using weak coherent pulses. By applying the method to Reference-Frame-Independent Measurement-Device-Independent Quantum Key Distribution, we experimentally verify the feasibility and effectiveness of the method.