Near-complete polarization Bell-state analysis based on symmetry-broken scheme with linear optics

TL;DR

This paper introduces a linear optics-based, symmetry-broken scheme capable of near-complete polarization Bell-state analysis with over 99.2% success probability using at least 8 photon pairs, advancing quantum communication techniques.

Contribution

It presents a novel symmetry-broken linear optics scheme for near-complete Bell-state discrimination without auxiliary means, achieving high success rates.

Findings

Deterministically identifies four Bell states with >99.2% success probability

Requires at least 8 photon pairs for high success rate

Simpler and feasible with current technology

Abstract

Bell-state analysis is a considerable challenge and an essential requirement for reliable implementation of quantum communication proposals. An open question is the one for the maximal fraction of successful Bell measurements. It has been pointed out that no scheme using only linear elements can implement a Bell state analyzer. Some effort has paid attention to the complete polarization-entangled Bell-state analysis using linear optics, with the aid of auxiliary means. Here we present a symmetry-broken scheme with linear optics only, without any aid of other auxiliary means, for discriminating polarization-entangled Bell states. Although our scheme is unable of realizing complete Bell-state measurement for less photon-pairs situation, it can deterministically identify four Bell states with success probabilities beyond 99.2% provided that photon-pairs are not less than 8. Our scheme as a significant breakthrough is simpler and feasible with respect to the current technology for the near-complete Bell-state analysis. Symmetry breaking is indispensable in our scheme as in other physical systems.