Dynamical preparation of EPR entanglement in two-well Bose-Einstein condensates

TL;DR

This paper proposes a method to generate and detect EPR entanglement in two-well Bose-Einstein condensates through a dynamical process involving spin squeezing and tunneling, with predictions supported by analytical and stochastic simulations.

Contribution

It introduces a novel dynamical scheme for creating EPR entanglement in BECs, combining spin squeezing and tunneling, and demonstrates its robustness through analytical and simulation methods.

Findings

Entanglement increases with atom number.

Strong tunneling enhances entanglement.

Entanglement persists despite nonlinear losses.

Abstract

We propose to generate Einstein-Podolsky-Rosen (EPR) entanglement between groups of atoms in a two-well Bose-Einstein condensate using a dynamical process similar to that employed in quantum optics. The local nonlinear S-wave scattering interaction has the effect of creating a spin squeezing at each well, while the tunneling, analogous to a beam splitter in optics, introduces an interference between these fields that results in an inter-well entanglement. We consider two internal modes at each well, so that the entanglement can be detected by measuring a reduction in the variances of the sums of local Schwinger spin observables. As is typical of continuous variable (CV) entanglement, the entanglement is predicted to increase with atom number, and becomes sufficiently strong at higher numbers of atoms that the EPR paradox and steering non-locality can be realized. The entanglement is predicted using an analytical approach and, for larger atom numbers, stochastic simulations based on truncated Wigner function. We find generally that strong tunnelling is favourable, and that entanglement persists and is even enhanced in the presence of realistic nonlinear losses.