Detection of continuous variable entanglement without coherent local oscillators

TL;DR

This paper introduces three criteria for detecting continuous variable entanglement without assuming coherent local oscillators, addressing common misconceptions and demonstrating robustness against large particle number fluctuations.

Contribution

The authors develop new entanglement detection criteria that do not rely on coherent local oscillators, applicable to realistic many-particle quantum systems.

Findings

Correct identification of entanglement depends on proper criteria.

Large number fluctuations do not hinder entanglement detection.

Simulations with 100 particles validate the criteria.

Abstract

We propose three criteria for identifying continuous variable entanglement between two many-particle systems with no restrictions on the quantum state of the local oscillators used in the measurements. Mistakenly asserting a coherent state for the local oscillator can lead to incorrectly identifying the presence of entanglement. We demonstrate this in simulations with 100 particles, and also find that large number fluctuations do not prevent the observation of entanglement. Our results are important for quantum information experiments with realistic Bose-Einstein condensates or in optics with arbitrary photon states.