Phase diagram of two-species Bose-Einstein condensates in an optical lattice

TL;DR

This paper analytically explores the phase diagram of two-species Bose-Einstein condensates in an optical lattice, revealing superfluid and insulator phases through solutions of coupled nonlinear Schrödinger equations.

Contribution

It provides an analytical determination of the phase diagram beyond the tight-binding approximation using macroscopic wave functions.

Findings

Identified superfluid and insulator phases in the phase diagram.

Derived analytical expressions for phase boundaries.

Described condensate wave functions as traveling matter waves.

Abstract

The exact macroscopic wave functions of two-species Bose-Einstein condensates in an optical lattice beyond the tight-binding approximation are studied by solving the coupled nonlinear Schrodinger equations. The phase diagram for superfluid and insulator phases of the condensates is determined analytically according to the macroscopic wave functions of the condensates, which are seen to be traveling matter waves.