Trionic phase of ultracold fermions in an optical lattice: A variational study

TL;DR

This paper explores the phase transition in ultracold three-color fermionic atoms in an optical lattice, revealing a shift from superconducting to trionic phases using a variational approach and dynamical mean field theory.

Contribution

It introduces a variational method to analyze the three-color Hubbard model, demonstrating a quantum phase transition and reformulating Gutzwiller theory with an exactly solvable effective field theory.

Findings

Identified a quantum phase transition between superconducting and trionic phases.

Reformulated Gutzwiller variational theory in terms of an effective three-body interaction field.

Solved the effective field theory exactly in infinite dimensions using dynamical mean field theory.

Abstract

To investigate ultracold fermionic atoms of three internal states (colors) in an optical lattice, subject to strong attractive interaction, we study the attractive three-color Hubbard model in infinite dimensions by using a variational approach. We find a quantum phase transition between a weak-coupling superconducting phase and a strong-coupling trionic phase where groups of three atoms are bound to a composite fermion. We show how the Gutzwiller variational theory can be reformulated in terms of an effective field theory with three-body interactions and how this effective field theory can be solved exactly in infinite dimensions by using the methods of dynamical mean field theory.