Center of mass rotation and vortices in an attractive Bose gas

TL;DR

This paper investigates the rotational behaviors of an attractively interacting Bose gas, revealing the conditions for vortex and center of mass rotational states, and analyzing the transition between these phases through analytical and numerical methods.

Contribution

It provides a combined analytical and numerical analysis of rotational states in an attractive Bose gas, including the phase transition and validity of the Gross-Pitaevskii equation.

Findings

Vortex and center of mass rotational states are identified in anharmonic traps.

The transition between these states is gradual and occurs along a calculable crossover line.

The Gross-Pitaevskii equation accurately describes the system in the rotating frame.

Abstract

The rotational properties of an attractively interacting Bose gas are studied using analytical and numerical methods. We study perturbatively the ground state phase space for weak interactions, and find that in an anharmonic trap the rotational ground states are vortex or center of mass rotational states; the crossover line separating these two phases is calculated. We further show that the Gross-Pitaevskii equation is a valid description of such a gas in the rotating frame and calculate numerically the phase space structure using this equation. It is found that the transition between vortex and center of mass rotation is gradual; furthermore the perturbative approach is valid only in an exceedingly small portion of phase space. We also present an intuitive picture of the physics involved in terms of correlated successive measurements for the center of mass state.