Entanglement detection from channel parameter estimation problem

TL;DR

This paper introduces a new criterion for detecting entanglement in multi-partite quantum systems using quantum Fisher information, applicable to various quantum channels and robust against decoherence.

Contribution

It generalizes existing entanglement detection methods from unitary to arbitrary one-parameter quantum channels, including open systems.

Findings

Criterion effectively detects entanglement in diverse quantum channels

Applicable to open quantum systems with decoherence

Illustrated through multiple example scenarios

Abstract

We derive a general criterion to detect entangled states in multi-partite systems based on the symmetric logarithmic derivative quantum Fisher information. This criterion is a direct consequence of the fact that separable states do not improve the accuracy upon estimating one-parameter family of quantum channels. Our result is a generalization of the previously known criterion for one-parameter unitary channel to any one-parameter quantum channel. We discuss several examples to illustrate our criterion. The proposed criterion is extended to the case of open quantum systems and we briefly discuss how to detect entangled states in the presence of decoherence.