Cavity assisted generation of sustainable macroscopic entanglement of ultracold gases

TL;DR

This paper explores how a cavity-assisted setup with two Bose-Einstein condensates can generate and sustain macroscopic entanglement, with potential for quantum information applications.

Contribution

It introduces a scheme for entangling spatially separated condensates via cavity-mediated interactions in a superradiant phase, including a method to probe entanglement through auxiliary mode squeezing.

Findings

Cavity-mediated interactions can entangle condensates despite photon losses.

Macroscopic entanglement persists with occasional sudden death and rebirth.

Auxiliary photon mode squeezing correlates with atomic entanglement.

Abstract

Prospects for reaching persistent entanglement between two spatially separated atomic Bose-Einstein condensates are outlined. The system set-up comprises of two condensates loaded in an optical lattice, which, in return, is confined within a high-Q optical resonator. The system is driven by an external laser that illuminates the atoms such that photons can scatter into the cavity. In the superradiant phase a cavity field is established and we show that the emerging cavity mediated interactions between the two condensates is capable of entangling them despite photon losses. This macroscopic atomic entanglement is sustained throughout the time-evolution apart from occasions of sudden deaths/births. Using an auxiliary photon mode and coupling it to a collective quadrature of the two condensates we demonstrate that the auxiliary mode's squeezing is proportional to the atomic entanglement and as such it can serve as a probe field of the macroscopic entanglement.