Two-step condensation of lattice bosons

TL;DR

This paper theoretically investigates Bose-Einstein condensation of lattice bosons in anisotropic traps, revealing conditions for two-step condensation and its dependence on trap and lattice anisotropy.

Contribution

It demonstrates that two-step condensation occurs at lower anisotropy levels in lattice bosons compared to ideal gases and clarifies the role of trap and lattice anisotropy.

Findings

Two-step condensation occurs at reduced trap anisotropy in lattice bosons.

Two-step condensation does not occur with highly anisotropic hopping in isotropic traps.

Single boson energy states help interpret the condensation behavior.

Abstract

We present a theoretical study of Bose-Einstein condensation in highly anisotropic harmonic traps. The bosons are considered to be moving in an optical lattice in an overall anisotropic harmonic confining potential. We find that two-step condensation occurs for lattice bosons at much reduced harmonic potential anisotropy when compared to the case of an ideal bose gas in an anisotropic harmonic confinement. We also show that when the bosons are in an isotropic harmonic confinement but with highly anisotropic hopping in the optical lattice, two-step condensation does not occur. We interpret some of our results using single boson density of energy states corresponding to the potentials faced by the bosons.