Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 4: Quantum gases: Fermions
Q 4.5: Vortrag
Montag, 17. März 2014, 11:30–11:45, DO24 Reuter Saal
Relaxation dynamics of a fermionic quantum gas with high spin — •Jasper Simon Krauser1, Nick Fläschner1, Klaus Sengstock1,2, Christoph Becker1,2, Ulrich Ebling3, Maciej Lewenstein3,4, and André Eckhardt5 — 1Institut für Laserphysik, Universität Hamburg, Germany — 2Zentrum für Optische Quantentechnologien, Universität Hamburg, Germany — 3Institut de Ciències Fotòniques, Castelldefels, Spain — 4Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain — 5Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany
The relaxation of a closed quantum system constitutes a fundamental question in many-body physics. We present a detailed study of relaxation dynamics in a fermionic quantum gas of 40K atoms with high spin. The fermions are initially prepared far from equilibrium occupying only a few spin states. This induces a complex relaxation dynamics towards an equal spin population; meanwhile the whole spin system provides a bath for the thermalization for its individual spin subsystems. Our experimental results yield a good agreement with a kinetic Boltzmann equation, derived from a microscopic approach without free parameters. We identify several collisional processes governing the dynamics on fully different time scales and demonstrate the high experimental control by tuning the crucial parameters of the system, e.g. density and magnetic field. Our results open the path to engineer an open system with controllable dissipation into empty subsystems.