Quantum dynamics of Raman-coupled Bose-Einstein condensates using Laguerre-Gaussian beams

TL;DR

This paper explores the quantum dynamics of Raman-coupled Bose-Einstein condensates driven by Laguerre-Gaussian beams, revealing how vortex motion and population transfer depend on initial symmetry and detuning.

Contribution

It introduces an effective two-state Hamiltonian for Raman-coupled condensates with orbital angular momentum and analyzes collapse, revivals, and vortex dynamics.

Findings

Revival period depends on initial symmetry of the condensate.

Vortex motion can reveal broken U(1) symmetry.

Coherent population transfer achieved via detuning sweep.

Abstract

We investigate the quantum dynamics of Raman-coupled Bose-Einstein condensates driven by laser beams that carry orbital angular momentum. By adiabatically eliminating the excited atomic state we obtain an effective two-state Hamiltonian for the coupled condensates, and quantization of the matter-wave fields results in collapse and revivals in the quantum dynamics. We show that the revival period depends on whether the initial nonrotating condensate displays broken U(1) symmetry or not, and that the difference may be detected by measuring the motion of quantized vortices that are nested in the density profile of the Raman-coupled condensates. We further study the steady-state population transfer using a linear sweep of the two-photon detuning, by which the atomic population is coherently transferred from an initial nonrotating state to the final vortex state.