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Kettmann, P. ; Hannibal, S. ; Croitoru, Mikhail D. ; Axt, Vollrath Martin ; Kuhn, Tilmann:
Pure Goldstone mode in the quench dynamics of a confined ultracold Fermi gas in the BCS-BEC crossover regime.
In: Physical Review A.
Bd. 96
(2017)
Heft 3
.
- 033618.
ISSN 1094-1622
DOI: https://doi.org/10.1103/PhysRevA.96.033618
Abstract
We present a numerical study of the dynamic response of a confined superfluid Fermi gas to a rapid change of the scattering length (i.e., an interaction quench). Based on a fully microscopic time-dependent density-matrix approach within the full Bogoliubov–de Gennes formalism that includes a 3D harmonic confinement we simulate and identify the emergence of a Goldstone mode of the BCS gap in a cigar-shaped 6Li gas. By analyzing this Goldstone mode over a wide range of parameters, we show that its excitation spectrum is gapless and that its main frequency is not fixed by the trapping potential but that it is determined by the details of the quench. Thus we report the emergence of a pure Goldstone mode of the BCS gap that—in contrast to situations in many previous studies—maintains its gapless excitation spectrum predicted by the Goldstone theorem. Furthermore, we observe that the size-dependent superfluid resonances resulting from the atypical BCS-BEC crossover have a direct impact on this Goldstone mode. Finally, we find that the interaction quench-induced Goldstone mode leads to a low-frequency in-phase oscillation of the single-particle occupations with complete inversion of the lowest-lying single-particle states which could provide a convenient experimental access to the pure gapless Goldstone mode.
Weitere Angaben
| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Keywords: | Goldstone mode; ultracold confined Fermi gas; BCS regime; quench dynamics; BCS-BEC crossover; Bogoliubov–de Gennes formalism; microscopic time-dependent density-matrix approach |
| Institutionen der Universität: | Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Theoretische Physik III > Lehrstuhl Theoretische Physik III - Univ.-Prof. Dr. Martin Axt Fakultäten Fakultäten > Fakultät für Mathematik, Physik und Informatik Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Theoretische Physik III |
| Titel an der UBT entstanden: | Ja |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik > 530 Physik |
| Eingestellt am: | 06 Nov 2017 13:04 |
| Letzte Änderung: | 03 Aug 2023 12:02 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/40304 |