Strongly correlated quantum phases in ultracold mixtures of bosons and fermions in an optical lattice

Seiji Sugawa

Immanuel Bloch

Laurent Sanchez-Palencia, V. Ahufinger, Adrian Kantian +3 more

We investigate theoretically the low-temperature physics of a two-component ultracold mixture of bosons and fermions in disordered optical lattices. We focus on the strongly correlated regime. We show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. The composite picture is used to derive an effective Hamiltonian whose parameters can be controlled via the boson-boson and the boson-fermion interactions, the tunneling terms and the inhomogeneities. We finally investigate the quantum phase diagram of the composite fermions and we show that it corresponds to the formation of Fermi glasses, spin glasses, and quantum percolation regimes.

Sebastian Will, B. Paredes, Lucia Hackermüller +4 more

Immanuel Bloch, Achim Rosch

Abstract Ultracold quantum gases in optical lattices can be used as novel model system for the exploration of strongly correlated many‐body phases of bosonic or fermionic particles. Here we report on the realization of metallic, Mott‐insulating and band insulating phases in ultracold spin mixtures of fermionic 40K atoms. The experimental results are compared to ab initio dynamical mean field theory (DMFT) calculations.

Immanuel Bloch