Entanglement of Local Hidden States

TL;DR

This paper develops experimentally feasible criteria to detect multipartite entanglement in local hidden states, revealing that separable states can harbor hidden entanglement unlockable through measurements, even without steering.

Contribution

It introduces new criteria for quantifying multipartite entanglement in LHS models, highlighting hidden entanglement in separable states that can be activated by measurements.

Findings

Separable states can contain hidden entanglement.

Measurements on one system can unlock entanglement in another.

Criteria provide quantitative bounds on multipartite entanglement in LHS.

Abstract

Steering criteria are conditions whose violation excludes the possibility of describing the observed measurement statistics with local hidden state (LHS) models. When the available data do not allow to exclude arbitrary LHS models, it may still be possible to exclude LHS models with a specific separability structure. Here, we derive experimentally feasible criteria that put quantitative bounds on the multipartite entanglement of LHS. Our results reveal that separable states may contain hidden entanglement that can be unlocked by measurements on another system, even if no steering between the two systems is possible.