Quantum phase transition in a multi-component Bose-Einstein condensate in optical lattices

TL;DR

This paper develops a lattice model for multi-component Bose-Einstein condensates in optical lattices and analytically explores the quantum phase transition between Mott insulator and superfluid phases, highlighting the effects of inter-species interactions.

Contribution

It introduces a comprehensive lattice model and mean-field analysis for multi-component BECs, revealing how inter-species interactions influence phase separation and the phase diagram.

Findings

Strong inter-species interactions cause phase separation in the Mott insulator.

Weak interactions lead to a miscible multi-species system.

The tips of the Mott lobes are unaffected by inter-species interactions.

Abstract

We present the general lattice model for a multi-component atomic Bose-Einstein system in the optical lattice. Using the model, we analytically study the quantum phase transition between Mott insulator and superfluid. A mean-field theory is developed from the Mott insulator ground state. When the inter-species interactions are strong enough, the Mott insulator demonstrates the phase separation behavior. For weak inter-species interactions, the multi species system is miscible. Finally, the phase diagram is discussed with the emphasis on the role of inter-species interactions. The tips of the Mott insulator lobes do not depend on the inter-species interactions, but they indeed modify the range of lobes.