Hannover 2020 – scientific programme

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A: Fachverband Atomphysik

A 27: Ultra-cold atoms, ions, and BEC VI (joint session A/Q)

A 27.5: Talk

Thursday, March 12, 2020, 15:15–15:30, f303

Coherent control in a driven Fermi-Hubbard system — •Anne-Sophie Walter, Frederik Görg, Kilian Sandholzer, Joaquín Minguzzi, Konrad Viebahn, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, Switzerland

Coherent control is a widely applied technique in fields ranging from chemistry to ultracold atoms. It aims at steering quantum dynamics by controlling the relative phase between external light fields. In the context of Floquet engineering in optical lattices, where the system is periodically driven in time, the drive can resonantly couple to higher Bloch bands leading to atom loss. To overcome this problem we apply a coherent control scheme which would allow for a wider range of possible driving frequencies.

In our experiment, we periodically modulate the potential depth of our 3D optical lattice at a frequency that excites atoms to a higher band. We apply coherent control by tuning the phase of an additional drive at twice the fundamental frequency which destructively interferes with the first. Through this technique we preserve both the band population as well as the fraction of double occupancies for two orders of magnitude longer compared to the single-frequency case. We find this technique to be effective even at strong Hubbard interactions. Strikingly, the lifetime of spin correlations, which are highly susceptible to heating, is also improved by two orders of magnitude and comparable to the static value. This successful application of coherent control in a periodically driven many-body system opens new possibilities for Floquet engineering in the presence of strong interactions.