Revealing of hidden quantum steerability using local filtering operations

TL;DR

This paper explores how local filtering operations can reveal hidden quantum steerability in states that appear unsteerable, demonstrating that certain filters are more effective than Bell nonlocality tests and uncovering counter-intuitive behaviors in mixed states.

Contribution

It introduces a method to reveal hidden quantum steerability using local filters, with experimental validation and comparison to Bell nonlocality.

Findings

Local filters can reveal steerability in initially unsteerable states.

Certain filters outperform Bell nonlocality tests in revealing steerability.

Mixed states from non-maximally entangled states can have hidden steerability.

Abstract

Nonlocal quantum correlation is at the heart of bizarre nature of quantum physics. While there are various classes of nonlocal quantum correlation, steerability of a quantum state by local measurements provides unique operational features. Here, we theoretically and experimentally investigate the hidden quantum steerability. In particular, we find that there are initially unsteerable states which can reveal the steerability by using local filters on individual quantum systems. It is remarkable that a certain set of local filters are more effective on revealing steerability than Bell nonlocality whereas there exists another set of filters that is more effective on revealing Bell nonlocality than steerability. Finally, we present a counter-intuitive result that mixed states originating from non-maximally pure entangled states can have hidden steerability while the mixed state from a maximally pure entangled state fails to show steerability.