Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 31: Poster: Quantum Optics and Photonics I
Q 31.9: Poster
Dienstag, 7. März 2017, 17:00–19:00, P OG1+2
Goldstone mode in the quench dynamics of an ultracold BCS Fermi gas: A full Bogoliubov-de Gennes approach — •Peter Kettmann1, Simon Hannibal1, 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 are a convenient system to probe and study the properties of phases like the BEC and the BCS phase and the crossover in between those regimes. In particular, ultracold Fermi gases can be used as a test bed to study the two fundamental dynamical modes –the Higgs and the Goldstone mode– which result from spontaneous symmetry breaking in these phases.
We investigate the Goldstone mode in the dynamics of a cigar-shaped cloud of ultracold 6Li after an interaction quench on the BCS side of the BCS-BEC crossover. To this end, we numerically solve Heisenberg’s equations of motion for the Bogoliubov single-particle excitations in the framework of the Bogoliubov-de Gennes (BdG) formalism. Extending previous studies, we use a full BdG approach instead of the truncated Anderson solution. This improves the validity in the strong-coupling regime and ensures a correct coupling of the Goldstone mode to the trapping potential.
We study the impact of this extension on the dynamics of the single-particle excitations and find an overall good qualitative agreement of both solutions. However, some significant deviations occur predominantly in the case of strong coupling.