Ground-state and Excitation spectra of Bose-Fermi Mixtures in a Three-Dimensional Optical Lattice

TL;DR

This paper explores the phase diagrams and excitation spectra of Bose-Fermi mixtures in a 3D optical lattice, revealing new coexisting phases and characteristic spectral features through theoretical analysis.

Contribution

It introduces a new coexisting phase of superfluid bosons and metal fermions using the Gutzwiller approximation and analyzes their excitation spectra.

Findings

Identification of a new coexisting phase with superfluid bosons and metal fermions

Distinct excitation features in Mott insulator and superfluid phases

Gapless modes in the coexisting phase affected by interactions

Abstract

Motivated by recent developments in the experimental study of Bose-Fermi mixtures, we investigate ground-state phase diagrams and excitation spectra for Bose-Fermi mixtures in a three-dimensional (3D) optical lattice. The Gutzwiller approximation is used to identify a new phase in which both superfluid bosons and metal fermions coexist. As a useful probe to identify the quantum phases, we also calculate the excitation spectra. In Mott insulator phase, two excitation features appear in the spectra that correspond to particle and hole excitations. In superfluid phase, there are Bogoliubov modes and amplitude modes. In coexisting phase, two gapless dispersive modes are identified, which shift due to interaction between bosons and fermions.