Ground state properties of a three-site Bose-Fermi ring with a small number of atoms

TL;DR

This paper studies a small quantum Bose-Fermi system on a three-site ring, revealing how interactions influence ground state symmetry and lead to unique insulating phases even under strong tunneling conditions.

Contribution

It provides an exact diagonalization analysis of the Bose-Fermi-Hubbard model, uncovering interaction-dependent ground state symmetries and novel insulating phases in a minimal ring system.

Findings

Ground state symmetry depends on boson-boson and inter-species interactions.

Existence of nontrivial insulating phases at strong tunneling and incommensurate filling.

Insulating phases can occur without suppression of particle number fluctuations.

Abstract

We investigate a three-site ring system with a small number of quantum degenerate bosons and fermions. By means of the exact diagonalization of the Bose-Fermi-Hubbard Hamiltonian, we show that the symmetry of the ground state configuration is a function of both the boson-boson and the inter-species interaction in the system. The phase diagram of the system, constructed by computing the exact two-body spatial correlations, reveals nontrivial insulating phases that exist even in the strong bosonic tunneling limit and for incommensurate filling of bosons. These insulating phases are due to the inter-species interactions in the system and are not necessarily accompanied by the suppression of the particle number fluctuations.