Universität zu Köln

Bamler, Robert ORCID: 0000-0002-3135-8107 and Rosch, Achim ORCID: 0000-0002-6586-5721 (2015). Equilibration and approximate conservation laws: Dipole oscillations and perfect drag of ultracold atoms in a harmonic trap. Phys. Rev. A, 91 (6). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1094-1622

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Abstract

The presence of (approximate) conservation laws can prohibit the fast relaxation of interacting many-particle quantum systems. We investigate this physics by studying the center-of-mass oscillations of two species of fermionic ultracold atoms in a harmonic trap. If their trap frequencies are equal, a dynamical symmetry (spectrum-generating algebra), closely related to Kohn's theorem, prohibits the relaxation of center-of-mass oscillations. A small detuning delta omega of the trap frequencies for the two species breaks the dynamical symmetry and ultimately leads to a damping of dipole oscillations driven by interspecies interactions. Using memory-matrix methods, we calculate the relaxation as a function of frequency difference, particle number, temperature, and strength of interspecies interactions. When interactions dominate, there is almost perfect drag between the two species and the dynamical symmetry is approximately restored. The drag can either arise from Hartree potentials or from friction. In the latter case (hydrodynamic limit), the center-of-mass oscillations decay with a tiny rate, 1/tau proportional to (delta omega)(2)/Gamma, where Gamma is a single-particle scattering rate.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bamler, Robert UNSPECIFIED orcid.org/0000-0002-3135-8107 UNSPECIFIED Rosch, Achim UNSPECIFIED orcid.org/0000-0002-6586-5721 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-401257
DOI:	10.1103/PhysRevA.91.063604
Journal or Publication Title:	Phys. Rev. A
Volume:	91
Number:	6
Date:	2015
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1094-1622
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ELECTRON-GAS; TRANSPORT Multiple languages Optics; Physics, Atomic, Molecular & Chemical Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/40125