Detecting entanglement in two mode squeezed states by particle counting

TL;DR

This paper introduces a particle counting-based entanglement criterion for two mode squeezed states, enabling feasible detection of atomic entanglement without quadrature measurements and applicable to various experimental setups.

Contribution

It proposes an optimal, loss-robust entanglement criterion relying solely on particle counting, bridging discrete and continuous variable entanglement verification methods.

Findings

Criterion is optimal for the considered states.

Robust against particle losses up to 2/3.

Applicable to atomic and light entanglement in BEC experiments.

Abstract

We present an entanglement criterion for two mode squeezed states which relies on particle counting only. The proposed inequality is optimal for the state under consideration and robust against particle losses up to 2/3. As it does not involve measurements of quadratures - which is typically very challenging for atomic modes - it renders the detection of atomic many-particle entanglement feasible in many different settings. Moreover it bridges the gap between entanglement verification for a qubit and criteria for continuous variables measured by homodyne detection. We illustrate its application in the context of superradiant light scattering from Bose Einstein condensates by considering the creation of entanglement between atoms and light as well as between two condensates in different momentum states. The latter scheme takes advantage of leaving the Gaussian realm and features probabilistic entanglement distillation.