A system of ultracold atoms can be brought in contact with a thermal bath by letting it interact weakly with a large cloud of another atomic species. We consider atoms in a time-periodically driven optical lattice in contact with an interacting Bose condensate and microscopically model them using Floquet-Born-Markov theory. The interplay of driving and dissipation will guide these systems into non-equilibrium steady states. Compared to the usual adiabatic state preparation, suffering from non-adiabatic excitation processes, this scenario can have two advantages; it is robust, since energy (and entropy) can be dumped into the bath, and it allows for the preparation of interesting states beyond the strict constraints of thermal equilibrium. I will present two examples in rather different regimes: (i) In a system of fermions loaded into the Floquet-topological band structure of a hexagonal lattice created by high-frequency driving, the coupling to the environment allows to “cool” almost all particles into a single band so that a topological insulator giving rise to a quantized Hall response is prepared . (ii) Subjecting a one-dimensional bosonic system to a spatially local drive of intermediate frequency that resonantly excites (heats) the system, the interplay of driving and dissipation is found to give rise to the formation of a non-equilibrium Bose condensate in a subspace that approximately decouples from the drive . Finally, I will also address the (experimental and numerical) observation of a dynamical phase transition occurring at a critical time during the bath-induced relaxation dynamics of an open system .
 A. Schnell and A. Eckardt.: Stabilizing a Floquet topological insulator in a driven optical lattice by bath engineering (in preparation).
 A. Schnell, L.-N. Wu, A. Widera, A. Eckardt.: Floquet-heating-induced non-equilibrium Bose condensation in an open optical lattice (preprint, arXiv:2204.07147).
 L.-N. Wu, J. Nettersheim, J. Feß, A. Schnell, S. Burgardt, S. Hiebel, D. Adam, A.E., A. Widera, A. Eckardt: Dynamical phase transition in an open quantum system (in preparation).
|Presenter name||Eckardt, André|
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