Hannover 2016 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 61: Quantum Gases: Fermions II
Q 61.1: Talk
Friday, March 4, 2016, 11:00–11:15, e001
Realizing state-dependent optical lattices for ultracold fermions by periodic driving — •Frederik Görg1, Gregor Jotzu1, Michael Messer1, Daniel Greif1,2, Rémi Desbuquois1, and Tilman Esslinger1 — 1Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland — 2Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
Ultracold atoms in optical lattices offer the possibility to engineer specific Hamiltonians with widely tunable properties. Recently, time-modulated optical lattices have been used to dynamically control the atomic tunnelling and to realize effective Floquet lattice Hamiltonians with a non-trivial topological band structure. While previous implementations relied on the physical motion of the lattice potential, this effect can also be realized by a periodic modulation of a magnetic field gradient. As the coupling of an atom to this magnetic field gradient depends on its magnetic moment and therefore its internal state, the effective Hamiltonian is spin-dependent.
We realize a state-dependent lattice for fermionic potassium atoms and characterize the different band structures for each internal state by measuring the expansion rate of an atomic cloud in the lattice and the effective mass through dipole oscillations. Furthermore, we study the heating caused by the periodic driving in an interacting fermionic spin mixture and how it can be suppressed. This method of creating spin-dependent optical lattices can be used to create novel situations, such as systems where one fermionic spin state is pinned to the lattice, while the other remains itinerant.