Distrustful quantum steering

TL;DR

This paper explores how partial distrust in measurement devices affects quantum steering detection, revealing that even slight distrust can lead to false positives, especially in higher-dimensional systems.

Contribution

It introduces a framework to analyze the impact of measurement imprecision on quantum steering inequalities and local bounds, highlighting the importance of device trust in steering verification.

Findings

Small distrust can cause unsteerable states to appear steerable.

Imprecision affects the local bound of steering inequalities.

Higher dimensions amplify the effect of distrust on steering detection.

Abstract

Quantum steering is an asymmetric form of quantum nonlocality where one can trust the measurements of one of the parties. In this work, inspired by practical considerations we investigate the scenario if one can not fully trust their measurement devices but only up to some precision. We first find the effect of such an imprecision on standard device-dependent quantum tomography. We then utilise this result to compute the variation in the local bound of any general steering inequality depending on the amount of trust one puts in one of the party's measurement devices. This is particularly important as we show that even a small distrust on Alice might cause the parties to observe steerability even if the quantum state is unsteerable. Furthermore, this effect becomes more relevant when observing higher dimensional quantum steering.