Bose-Einstein condensate in an elliptical waveguide

TL;DR

This paper explores how the curvature of an elliptical waveguide influences a Bose-Einstein condensate, revealing a quantum phase transition driven by interaction strength and curvature effects.

Contribution

It introduces an effective 1D model incorporating a quantum-curvature potential dependent on ellipse eccentricity, highlighting curvature's role in quantum phase transitions.

Findings

Ground state transitions from two peaks to one at critical interaction strength.

Superfluid fraction diminishes and vanishes with increasing attractive interactions.

Curvature significantly affects the quantum phase behavior of the condensate.

Abstract

We investigate the effects of spatial curvature for an atomic Bose-Einstein condensate confined in an elliptical waveguide. The system is well described by an effective 1D Gross-Pitaevskii equation with a quantum-curvature potential, which has the shape of a double-well but crucially depends on the eccentricity of the ellipse. The ground state of the system displays a quantum phase transition from a two-peak configuration to a one-peak configuration at a critical attractive interaction strength. In correspondence of this phase transition the superfluid fraction strongly reduces and goes to zero for a sufficiently attractive Bose-Bose interaction.