Erlangen 2018 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 35: Quantum Gases (Fermions) II
Q 35.4: Vortrag
Dienstag, 6. März 2018, 14:45–15:00, K 1.022
Enhancement and sign change of magnetic correlations in a driven quantum many-body system — •Frederik Görg1, Michael Messer1, Kilian Sandholzer1, Joaquín Minguzzi1, Gregor Jotzu1,2, Rémi Desbuquois1, and Tilman Esslinger1 — 1Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland — 2Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
Strong periodic driving can be used to control the properties of interacting quantum systems. In solid state experiments, ultrashort laser pulses are employed to tune the charge order as well as magnetic and superconducting properties of materials. At the same time, continuous driving has been used in cold atom experiments to engineer novel effective Floquet-Hamiltonians which feature for example a topological bandstructure. We realize a strongly interacting Fermi gas in a periodically driven hexagonal optical lattice and investigate its charge and magnetic properties. We first demonstrate that in the high-frequency regime, the effective description of the many-body system by a renormalized tunnelling amplitude remains valid by comparing our results to an equivalent static system. When driving at a frequency close to the interaction energy, we show that anti-ferromagnetic correlations can be enhanced or even switched to ferromagnetic ordering. Our observations can be explained by a microscopic model, in which the particle tunnelling and magnetic exchange energies can be controlled independently. Therefore, Floquet engineering constitutes an alternative route to experimentally investigate unconventional pairing.