Heidelberg 2015 – wissenschaftliches Programm
A 4.7: Vortrag
Montag, 23. März 2015, 16:00–16:15, C/HSW
Relaxation Dynamics of an Isolated Large-Spin Fermi Gas Far from Equilibrium — •Ulrich Ebling1,2, Jasper Simon Krauser3, Nick Fläschner3, Klaus Sengstock3,4, Christoph Becker3,4, Maciej Lewenstein2,5, and André Eckardt1 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany — 2ICFO - Institut de Ciències Fotòniques, Castelldefels, Spain — 3Institut für Laserphysik, Universität Hamburg, Hamburg, Germany — 4ZOQ - Zentrum für optische Quantentechnologien, Universität Hamburg, Hamburg, Germany — 5ICREA - Instituciò Catalana de Recerca i Estudis Avançats, Barcelona, Spain
A fundamental question in many-body physics is how closed quantum systems reach equilibrium. We address this question experimentally and theoretically in an ultracold large-spin Fermi gas where we find a complex interplay between internal and motional degrees of freedom. The fermions are initially prepared far from equilibrium with only a few spin states occupied. The subsequent dynamics leading to redistribution among all spin states is observed experimentally and simulated theoretically using a kinetic Boltzmann equation with full spin coherence. The latter is derived microscopically and provides good agreement with experimental data without any free parameters. We identify several collisional processes that occur on different time scales. By varying density and magnetic field, we control the relaxation dynamics and are able to continuously tune the character of a subset of spin states from an open to a closed system.