Experimental detection of steerability in Bell local states with two measurement settings

TL;DR

This paper investigates a fine-grained steering inequality to detect steerability in two-qubit states, demonstrating its effectiveness through numerical and experimental methods on Bell local states, which are typically challenging to analyze.

Contribution

It extends the application of a steering inequality to generalized Werner states and experimentally confirms steerability detection in Bell local states with only two measurement settings.

Findings

Successfully detected steerability in a wide range of Bell local states.

Validated the steering inequality through numerical simulations.

Performed experimental verification using two-photon polarization-entangled states.

Abstract

Steering, a quantum property stronger than entanglement but weaker than non-locality in the quantum correlation hierarchy, is a key resource for one-sided device-independent quantum key distribution applications, in which only one of the communicating parties is trusted. A fine-grained steering inequality was introduced in [PRA 90 050305(R) (2014)], enabling for the first time the detection of steering in all steerable two-qubit Werner states using only two measurement settings. Here we numerically and experimentally investigate this inequality for generalized Werner states and successfully detect steerability in a wide range of two-photon polarization-entangled Bell local states generated by a parametric down-conversion source.