Probing the quantumness of channels with mixed states

TL;DR

This paper introduces a resource-efficient testing method for quantum channels using effective entanglement, accommodating mixed states, and providing tight benchmarks through optimized measure-and-reprepare channels.

Contribution

It develops a new approach to benchmark quantum channels with mixed states, enhancing experimental feasibility and tightness of the benchmarks.

Findings

The proposed method requires minimal experimental resources.

Benchmarks are tight in relevant experimental regimes.

Optimized measure-and-reprepare channels improve testing accuracy.

Abstract

We present an alternative approach to the derivation of benchmarks for quantum channels, such as memory or teleportation channels. Using the concept of effective entanglement and the verification thereof, a testing procedure is derived which demands very few experimental resources. The procedure is generalized by allowing for mixed test states. By constructing optimized measure & re-prepare channels, the benchmarks are found to be very tight in the considered experimental regimes.