Entanglement witness via symmetric two-body correlations

TL;DR

This paper introduces a symmetric two-body correlation-based entanglement witness capable of detecting entanglement in Dicke and spin-squeezed states, demonstrating robustness and potential for experimental application.

Contribution

A novel entanglement witness using symmetric two-body correlations that detects entanglement in Dicke and spin-squeezed states, with robustness against noise and applicability to superpositions.

Findings

Detects entanglement in Dicke states for any number of particles.

Robust against white noise and thermal noise under the Lipkin-Meshkov-Glick Hamiltonian.

Effectively detects entanglement in spin-squeezed states, approaching maximal detection strength for large particle numbers.

Abstract

We construct an entanglement witness for many-qubit systems, based on symmetric two-body correlations with two measurement settings. This witness is able to detect the entanglement of some Dicke states for any number of particles, and such detection exhibits some robustness against white noise and thermal noise under the Lipkin-Meshkov-Glick Hamiltonian. In addition, it detects the entanglement of spin-squeezed states, with a detection strength that approaches the maximal value for sufficiently large numbers of particles. As spin-squeezed states can be experimentally generated, the properties of the witness with respect to these states may be amenable to experimental investigation. Finally, we show that while the witness is unable to detect GHZ states, it is instead able to detect superpositions of Dicke states with GHZ states.