Confinement vs Deconfinement of Cooper Pairs in One-Dimensional Spin-3/2 Fermionic Cold Atoms

TL;DR

This paper explores the phase diagram of one-dimensional spin-3/2 fermionic cold atoms, revealing confined and deconfined Cooper pair phases, an Ising transition, and novel insulating states through large-scale simulations.

Contribution

It provides the first large-scale numerical confirmation of the phase diagram, including the confinement transition and new insulating phases, in spin-3/2 fermionic cold atoms.

Findings

Identification of confined and deconfined Cooper pair phases

Discovery of an Ising quantum phase transition between phases

Revelation of a bond-ordered Mott insulator in the phase diagram

Abstract

The phase diagram of spin-3/2 fermionic cold atoms trapped in a one-dimensional optical lattice is investigated at quarter filling (one atom per site) by means of large-scale numerical simulations. In full agreement with a recent low-energy approach, we find two phases with confined and deconfined Cooper pairs separated by an Ising quantum phase transition. The leading instability in the confined phase is an atomic-density wave with subdominant quartet superfluid instability made of four fermions. Finally, we reveal the existence of a bond-ordered Mott insulating phase in some part of the repulsive regime.