Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 46: Quantum Gases: Fermions I
Q 46.4: Vortrag
Donnerstag, 9. März 2017, 12:00–12:15, P 204
Vanishing order parameter oscillations of the Higgs mode in a cigar-shaped ultracold Fermi gas — •Simon Hannibal1, Peter Kettmann1, Mihail Croitoru2, Vollrath Martin Axt3, and Tilmann Kuhn1 — 1Institute of Solid State Theory, University of Münster — 2Condensed Matter Theory, University of Antwerp — 3Theoretical Physics III, University of Bayreuth
Ultracold Fermi gases in optical traps provide a unique system to study the many body physics of systems composed of fermionic constituents. Both, the BEC and the BCS superfluid state are observed. Furthermore, the transition between these states is well controllable by means of a Feshbach resonance, which allows to tune the scattering length over a wide range from negative to positive values.
We employ an inhomogeneous BCS mean field theory and calculate the dynamics of the BCS gap of a confined ultracold Fermi gas after an interaction quench. Due to the spontaneously broken U(1) symmetry in the superfluid phase two fundamental modes of the BCS gap evolve, i.e., the amplitude (Higgs) and phase (Goldstone) mode. Here, we focus on the Higgs mode on the BCS side of the BCS-BEC crossover.
We investigate the dynamics after a large quench from strong to weak interactions. For large aspect ratios we find a dynamical vanishing of the order parameter similar to what has been predicted in the case of a homogeneous system. However, for smaller aspect ratios transverse trap modes are excited preventing a complete vanishing of the order parameter.