Fermionic atoms in a 3D optical lattice: Observing Fermi-surfaces, dynamics and interactions

TL;DR

This study explores the properties and dynamics of fermionic atoms in a 3D optical lattice, including Fermi surface imaging, phase transitions, and interaction effects, advancing understanding of quantum many-body systems.

Contribution

It provides direct imaging of Fermi surfaces, measures transition timescales, and demonstrates interaction-induced band coupling in a 3D optical lattice, revealing new quantum phenomena.

Findings

Fermi surface directly imaged in a 3D lattice

Transition from band insulator to normal state occurs over longer timescales than tunneling

Interaction-induced band coupling observed and shifted by confinement effects

Abstract

We have studied interacting and non-interacting quantum degenerate Fermi gases in a three-dimensional optical lattice. We directly image the Fermi surface of the atoms in the lattice by turning off the optical lattice adiabatically. Due to the confining potential gradual filling of the lattice transforms the system from a normal state into a band insulator which constitutes a high fidelity quantum register. The dynamics of the transition from a band insulator to a normal state is studied and the time scale is measured to be an order of magnitude larger than the tunneling time in the lattice. Using a Feshbach resonance we increase the interaction between atoms in two different spin states and dynamically induce a coupling between the lowest energy bands. We observe a shift of this coupling with respect to the Feshbach resonance in free space which is anticipated for strongly confined atoms.