Mott states under the influence of fermion-boson conversion: invasion of superfluidity

TL;DR

This paper investigates how fermion-boson conversion near Feshbach resonances affects Mott states of Cooper pairs, revealing the potential emergence of superfluidity and identifying distinct collective excitation modes.

Contribution

It introduces a coupled quantum rotor and spin Hamiltonian approach to analyze fermion-boson conversion effects on Mott states and superfluidity.

Findings

Fermion-boson conversion can induce superfluidity in Mott states.

Two branches of collective modes are identified, with one always gapped.

Anti-symmetric phase oscillations are a key feature of the collective excitations.

Abstract

I study the influence of fermion-boson conversion near Feshbach resonances on Mott states of Cooper pairs and demonstrate possible invasion of superfluidity. The quantum dynamics of Fermi-Bose gases is studied using both an effective coupled $U(1)\otimes U(1)$ quantum rotor Hamiltonian and a coupled XXZ $\otimes$ XXZ spin Hamiltonian. I also point out two distinct branches of collective modes in superfluid states, one of which involves anti-symmetric phase oscillations in fermionic and bosonic channels and is {\em always} gapped because of fermion-boson conversion.