Unified Approach to Witness Nonentanglement-Breaking Quantum Channels

TL;DR

This paper introduces a practical, unified method for certifying nonentanglement-breaking quantum channels, crucial for quantum technologies relying on entanglement, applicable across various experimental scenarios.

Contribution

It provides a necessary and sufficient condition for witnessing nonEB channels using a prepare-and-measure test, unifying and extending existing certification methods.

Findings

Applicable in almost all experimental scenarios

Simplifies existing certification methods

Enables certification in semi-device-independent scenarios

Abstract

The ability of quantum devices to preserve or distribute entanglement is essential in employing quantum technologies. Such ability is described and guaranteed by the nonentanglement-breaking (nonEB) feature of participating quantum channels. For quantum information applications relying on entanglement, the certification of the nonEB feature is thus indispensable in designing, testing, and benchmarking quantum devices. Here, we develop a direct and operational approach for the certification of nonEB quantum channels. By utilizing the prepare-and-measure test, we derive a necessary and sufficient condition for witnessing nonEB channels, which is applicable in almost all experimental scenarios. The approach not only unifies and simplifies existing methods in the standard scenario and the measurement-device-independent scenario, but also goes further allowing for certifying the nonEB feature in the semi-device-independent scenario.