Dissipative dynamics of a driven quantum spin coupled to a nonMarkovian bath of ultracold fermions.pdf

Dissipative dynamics of a driven quantum spin coupled to a non-Markovian bath of ultracold fermions Michael Knap,1, 2 Dmitry A. Abanin,1, 3 and Eugene Demler1 1Department of Physics, Harvard University, Cambridge MA 02138, USA 2ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA 3Perimeter Institute for Theoretical Physics, Waterloo, N2L2Y5 ON, Canada (Dated: June 14, 2013) We explore the dynamics and the steady-state of a driven quantum spin coupled to a bath of fermions, which can be realized with a strongly imbalanced mixture of ultra-cold atoms using cur- rently available experimental tools. Radio-frequency driving can be used to induce tunneling between the spin states. The Rabi oscillations are modified due to the coupling of the quantum spin to the environment, which causes frequency renormalization and damping. The spin-bath coupling can be widely tuned by adjusting the scattering length through a Feshbach resonance. When the scattering potential creates a bound state, by tuning the driving frequency it is possible to populate either the ground state, in which the bound state is filled, or a metastable state in which the bound state is empty. In the latter case, we predict an emergent inversion of the steady-state magnetization. Our work shows that different regimes of dissipative dynamics can be explored with a quantum spin coupled to a bath of ultracold fermions. PACS numbers: 47.70.Nd, 67.85.-d, 71.10.Pm, 72.10.-d Systems of ultracold atoms provide a versatile labo- ratory to explore real-time many-body dynamics due to their long coherence times and tunability [1, 2] and in particular allow one to study rich impurity physics [3– 6]. In the recent years, much progress has been achieved in realizing quantum impurities interacting with many- body environments. Examples include quantum degener- ate gases consisting of a single atom type, where a small fraction of the atoms is transfered to a different hyper- fine state [7–11], ions im