Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 58: Poster: Quantum Optics and Photonics IV
Q 58.75: Poster
Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof
Confinement-induced effects on the Higgs mode of an ultracold Fermi gas after a quench — •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 in these systems. Furthermore, the transition between these two states is well controllable by means of a Feshbach resonance, which allows one to tune the interaction strength over a wide range from negative to positive scattering lengths.
We employ an inhomogeneous BCS mean field theory and calculate the dynamics of the BCS gap of a confined ultracold Fermi gas after a quantum quench, i.e., a sudden change of the coupling constant. 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 regime.
We find damped collective amplitude oscillations of the gap breaking down after a certain time. Depending on the quench parameters we investigate the damping and fragmentation of the Higgs mode exploiting a set of linearized equations of motions. Thereby, we illuminate the impact of the confinement on the dynamics of a BCS-BEC system.