Reliable and robust entanglement witness

TL;DR

This paper introduces a measurement-device-independent entanglement witness scheme that enhances reliability and robustness in detecting quantum entanglement, optimizing conclusions based on experimental data without changing the measurement process.

Contribution

It proposes a novel entanglement witness method that improves reliability and robustness by combining measurement-device independence with data-driven optimization.

Findings

Achieves measurement-device independence for entanglement witnessing.

Optimizes entanglement detection based on experimental data.

Enhances reliability and robustness in practical quantum scenarios.

Abstract

Entanglement, a critical resource for quantum information processing, needs to be witnessed in many practical scenarios. Theoretically, witnessing entanglement is by measuring a special Hermitian observable, called entanglement witness (EW), which has non-negative expected outcomes for all separable states but can have negative expectations for certain entangled states. In practice, an EW implementation may suffer from two problems. The first one is \emph{reliability}. Due to unreliable realization devices, a separable state could be falsely identified as an entangled one. The second problem relates to \emph{robustness}. A witness may not to optimal for a target state and fail to identify its entanglement. To overcome the reliability problem, we employ a recently proposed measurement-device-independent entanglement witness, in which the correctness of the conclusion is independent of the implemented measurement devices. In order to overcome the robustness problem, we optimize the EW to draw a better conclusion given certain experimental data. With the proposed EW scheme, where only data postprocessing needs to be modified comparing to the original measurement-device-independent scheme, one can efficiently take advantage of the measurement results to maximally draw reliable conclusions.