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Persistent oscillations of the order parameter and interaction quench phase diagram for a confined Bardeen-Cooper-Schrieffer Fermi gas

Title data

Hannibal, S. ; Kettmann, P. ; Croitoru, Mikhail D. ; Axt, Vollrath Martin ; Kuhn, T.:
Persistent oscillations of the order parameter and interaction quench phase diagram for a confined Bardeen-Cooper-Schrieffer Fermi gas.
In: Physical Review A. Vol. 98 (November 2018) Issue 5 . - Eintrag 053605.
ISSN 0556-2791
DOI: https://doi.org/10.1103/PhysRevA.98.053605

Abstract in another language

We present a numerical study of the interaction quench dynamics in a superfluid ultracold Fermi gas confined in a three-dimensional cigar-shaped harmonic trap. In the present paper, we investigate the amplitude mode of the superfluid order parameter after interaction quenches, which start deep in the BCS phase and end in the BCS-BEC-crossover regime. To this end, we exploit the Bogoliubov–de Gennes formalism, which takes the confinement potential explicitly into account and provides a microscopic fully coherent description of the system. We find an anharmonic nonlinear oscillation of the modulus of the superfluid order parameter, i.e., of the Higgs mode. This oscillation persists for large times with only a small amplitude modulation being visible. We connect the frequency and the mean value of this oscillation with the breaking of Cooper pairs in the superfluid phase. Additionally, we demonstrate that the occurrence of this persistent oscillation is connected to the onset of chaotic dynamics in our model. Finally, we calculate an interaction quench phase diagram of the Higgs mode for quenches on the BCS side of the BCS-BEC crossover and discuss its properties as a function of the aspect ratio of the cigar-shaped trap.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Higgs mode; ultracold confined Fermi gas; BCS regime; quench dynamics; nonlinear order parameter oscillations; chaotic dynamics; BCS-BEC crossover, Bogoliubov–de Gennes formalism; microscopic time-dependent density-matrix approach
Subject classification: condensed matter physics (theoretical)
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 14 Nov 2018 07:35
Last Modified: 14 Nov 2018 07:35
URI: https://eref.uni-bayreuth.de/id/eprint/46317