Pairing of 1D Bose-Fermi mixtures with unequal masses

TL;DR

This study uses DMRG to analyze a 1D Bose-Fermi mixture with unequal masses, revealing phase transitions and a novel paired phase that could be experimentally detected.

Contribution

It provides the first detailed phase diagram for unequal mass Bose-Fermi mixtures and identifies a new paired phase with specific correlation properties.

Findings

Transition between Luttinger liquid and collapsed phases

Existence of an intermediate paired phase

Correlation functions indicating composite particles

Abstract

We have considered one-dimensional Bose-Fermi mixture with equal densities and unequal masses using numerical density matrix renormalization group (DMRG). For the mass ratio of K-Rb mixture and attraction between bosons and fermions, we determined the phase diagram. For weak boson-boson interactions, there is a direct transition between two-component Luttinger liquid and collapsed phases as the boson-fermion attraction is increased. For strong enough boson-boson interactions, we find an intermediate "paired" phase, which is a single-component Luttinger liquid of composite particles. We investigated correlation functions of such a "paired" phase, studied the stability of "paired" phase to density imbalance, and discussed various experimental techniques which can be used to detect it.