Hierarchical dimensional crossover of an optically-trapped quantum gas with disorder

TL;DR

This paper investigates the hierarchical crossover of a quantum gas from three dimensions to quasi-two and one dimensions using an anisotropic optical lattice, providing analytical insights into ground-state properties and quantum fluctuations.

Contribution

It analytically characterizes the dimensional crossover in a 3D Bose-Einstein condensate trapped in an anisotropic optical lattice, including ground-state energy, depletion, and superfluid density.

Findings

Demonstrates the 3D to 2D to 1D crossover in quantum fluctuations

Provides analytical expressions for ground-state energy and superfluid density

Discusses experimental conditions for observing these crossovers

Abstract

Dimensionality serves as an indispensable ingredient in any attempt to formulate the low-dimensional physics, and studying the dimensional crossover at a fundamental level is challenging. The purpose of this work is to study the hierarchical dimensional crossovers, namely the crossover from three dimensions (3D) to quasi-2D and then to 1D. Our system consists of a 3D Bose-Einstein condensate (BEC) trapped in an anisotropic 2D optical lattice characterized by the lattice depths $V_1$ along the $x$ direction and $V_2$ along the $y$ direction, respectively, where the hierarchical dimensional crossover is controlled via $V_1$ and $V_2$. We analytically derive the ground-state energy, quantum depletion and the superfluid density of the system. Our results demonstrate the 3D-quasi-2D-1D dimensional crossovers in the behavior of quantum fluctuations. Conditions for possible experimental realization of our scenario are also discussed.