The ground state of a mixture of two species of fermionic atoms in 1D optical lattice

TL;DR

This paper studies the ground state of a two-species fermionic atom mixture in 1D optical lattices, revealing phase transitions and stability conditions relevant for cold-atomic and heavy fermion systems.

Contribution

It provides a rigorous proof of phase separation stability in the asymmetric Hubbard model at infinite U, and analyzes the quantum phase transition from density wave to phase separation.

Findings

Density wave is unstable to phase separation at infinite U with single hole doping.

Quantum phase transition from density wave to phase separation is characterized.

Results are relevant for cold-atomic experiments and heavy fermion systems.

Abstract

In this paper, we investigate the ground state properties of a mixture of two species of fermionic atoms in one-dimensional optical lattice, as described by the asymmetric Hubbard model. The quantum phase transition from density wave to phase separation is investigated by studying both the corresponding charge order parameter and quantum entanglement. A rigorous proof that even for the single hole doping case, the density wave is unstable to the phase separation in the infinite U limit, is given. Therefore, our results are quite instructive for both on-going experiments on strongly correlated cold-atomic systems and traditional heavy fermion systems.