Expansion dynamics of Fermi atoms in optical lattice

Masahiko Okumura, Hiroaki Onishi, S. Yamada +1 more

Georg A. Raithel, G. Birkl, William D. Phillips +1 more

Pia Siegl, S. I. Mistakidis, Peter Schmelcher

We unravel the correlated nonequilibrium dynamics of a mass balanced Bose-Fermi mixture in a one-dimensional optical lattice upon quenching an imposed harmonic trap from strong to weak confinement. Regarding the system's ground state, the competition between the inter- and intraspecies interaction strength gives rise to the immiscible and miscible phases characterized by negligible and complete overlap of the constituting atomic clouds, respectively. The resulting dynamical response depends strongly on the initial phase and consists of an expansion of each cloud and an interwell tunneling dynamics. For varying quench amplitude and referring to a fixed phase, a multitude of response regimes is unveiled, being richer within the immiscible phase, which are described by distinct expansion strengths and tunneling channels.

J. Krauser, Jannes Heinze, Nick Fl aschner +3 more

S. Langer, Fabian Heidrich‐Meisner, A Sommerfeld

We show that in the sudden expansion of a spin-balanced two-component Fermi gas in an optical lattice induced by releasing particles from a trap, over a wide parameter regime, the radius Rn of the particle cloud grows linearly in time. This allow us to define the expansion velocity Vex from Rn = Vext. The goal of this work is to clarify the dependence of the expansion velocity on the initial conditions which we establish from time-dependent density matrix renormalization group simulations, both for a box trap and a harmonic trap. As a prominent result, the presence of a Mott-insulating region leaves clear fingerprints in the expansion velocity. Our predictions can be verified in experiments with ultra-cold atoms.

Michael Köhl, Henning Moritz, Thilo Stöferle +2 more