Quantum steering inequality with tolerance for measurement-setting-errors: experimentally feasible signature of unbounded violation

TL;DR

This paper introduces an experimentally feasible quantum steering inequality that tolerates measurement errors, demonstrating unbounded violation and potential applications in quantum randomness and technology.

Contribution

It derives a universal steering inequality with built-in error tolerance, applicable to multi-particle systems, advancing experimental verification of quantum correlations.

Findings

Demonstrates unbounded violation of the steering inequality

Provides a universal form incorporating measurement-error tolerance

Opens avenues for quantum randomness certification and technologies

Abstract

Quantum steering is a relatively simple test for quantumness of correlations, proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations Alice can influence -- steer -- Bob's physical system in a way inaccessible in classical world, leading to violation of some inequalities. Demonstrating this and similar quantum effects for systems of increasing size, approaching even the classical limit, is a long-standing challenging problem. Here we provide experimentally feasible signature of unbounded violation of a steering inequality. We derive its universal form where tolerance for measurement-setting-errors is explicitly build-in by means of the Deutsch-Maassen-Uffink uncertainty relation. Then, generalizing the mutual unbiasedness, we apply the inequality to the multi-singlet and multi-particle bipartite Bell-state. However, the method is general and opens the possibility of employing multi-particle bipartite steering for randomness certification and development of quantum technologies, e.g.\ random access codes.