An Artificial Frustrated System: Cold Atoms in 2D Triangular Optical Lattice

TL;DR

This paper explores the phase transition and electronic properties of cold atoms in a 2D triangular optical lattice, revealing a transition from Fermi liquid to Mott insulator with Kondo effects, using advanced computational methods.

Contribution

It introduces a combined dynamical cluster approximation and quantum Monte Carlo approach to study strongly correlated cold atoms in triangular lattices, highlighting new quantum phase behaviors.

Findings

Suppression of double occupancy with increased interaction

Transition from Fermi liquid to Mott insulator with a gap opening

Reentrant pseudogap behavior due to the Kondo effect

Abstract

We investigate the strongly correlated effect of cold atoms in triangular optical lattice by dynamical cluster approximation combining with the continuous time quantum Monte Carlo method proposed recently. It is found the double occupancy is suppressed as the atomic interaction increases. By calculating the density of states, we show how the system evolves from Fermi liquid with an obvious quasi-particle peak into Mott insulator with an opened gap for increasing interaction. The transition between Fermi liquid and pseudogap shows a reentrant behavior due to the Kondo effect. At low temperature, a Kondo peak appears before the splitting of the Fermi-liquid-like peak. The Fermi surface evolves from a circular ring with high amplitude into a {\deg}at elliptical ring with low amplitude for the increasing interaction. We give an experimental protocol to observe these phenomena by varying the lattice depth and the atomic interaction via Feshbach resonance in future experiments.