# Optical and atomic decoherence in entangled atomic ensembles generated by quantum nondemolition measurements

## TL;DR

This paper investigates how optical and atomic decoherence affect entangled atomic ensembles generated by quantum nondemolition measurements, revealing the robustness of entanglement and non-classical correlations under various decoherence channels.

## Contribution

It provides a detailed analysis of decoherence effects on entangled atomic ensembles using Kraus operators and demonstrates the resilience of quantum correlations in QND-generated entanglement.

## Key findings

- Entanglement and correlations decay smoothly with decoherence.
- Non-classical properties persist under short interaction times.
- QND measurements are promising for entangling Bose-Einstein condensates.

## Abstract

We study the effects of decoherence in the form of optical phase diffusion, photon loss and gain, and atomic dephasing in entangled atomic ensembles produced via quantum nondemolition (QND) measurements. For the optical decoherence channels, we use the technique of integration within ordered operators (IWOP) to obtain the Kraus operators that describe the decoherence. We analyze the effect of different decoherence channels on a variety of quantities such as the variances of the spin operators, entanglement and correlation criteria, logarithmic negativity, and the Bell-CHSH inequality. We generally find a smooth decay of correlations and entanglement in the presence of decoherence. We find that various quantities retain showing non-classical properties under all three types of decoherence, in the short interaction time range. Our results show that such QND measurements are one of the most promising methods for entanglement generation between two Bose-Einstein condensates.