Feasibility of loophole-free nonlocality tests with a single photon

TL;DR

This paper investigates the practicality of conducting loophole-free Bell tests using a single photon distributed among multiple parties, focusing on efficiency thresholds and measurement schemes to challenge local realism.

Contribution

It introduces a general error model and analyzes the feasibility of Bell tests with a W-state shared by multiple parties, including specific optical measurement strategies.

Findings

Derived efficiency thresholds for local realism violation

Analyzed two concrete optical measurement schemes

Provided insights into loss tolerance for Bell tests

Abstract

Recently much interest has been directed towards designing setups that achieve realistic loss thresholds for decisive tests of local realism, in particular in the optical regime. We analyse the feasibility of such Bell tests based on a W-state shared between multiple parties, which can be realised for example by a single photon shared between spatial modes. We develop a general error model to obtain thresholds on the efficiencies required to violate local realism, and also consider two concrete optical measurement schemes.