Superfluidity of a laser-stirred Bose-Einstein condensate

authored by: Hannes Kiehn, Vijay Pal Singh, Ludwig Mathey
Abstract: We study superfluidity of a cigar-shaped Bose-Einstein condensate by stirring it with a Gaussian potential oscillating back and forth along the axial dimension of the condensate, motivated by experiments of Raman et al. [Phys. Rev. Lett. 83, 2502 (1999)0031-900710.1103/PhysRevLett.83.2502]. Using classical-field simulations and perturbation theory, we examine the induced heating rate, based on the total energy of the system, as a function of the stirring velocity v. We identify the onset of dissipation by a sharply increasing heating rate above a velocity vc, which we define as the critical velocity. We show that vc is influenced by the oscillating motion, the strength of the stirrer, the temperature, and the inhomogeneous density of the cloud. This results in a vanishing vc for the parameters similar to the experiments, which is inconsistent with the measurement of nonzero vc. However, if the heating rate is based on the thermal fraction after a 100ms equilibration time, our simulation recovers the experimental observations. We demonstrate that this discrepancy is due to the slow relaxation of the stirred cloud and dipole mode excitation of the cloud.
Organisation(s): QuantumFrontiers
External Organisation(s): Universität Hamburg
Type: Article
Journal: Physical Review A
Volume: 105
ISSN: 2469-9926
Publication date: 25.04.2022
Publication status: Published
Peer reviewed: Yes
Electronic version(s): https://doi.org/10.48550/arXiv.2110.14634 (Access: Open)
https://doi.org/10.1103/PhysRevA.105.043317 (Access: Closed)

BibTeX

@article{fd88e016a194491f8b65eaa5aa6697ad,
title = "Superfluidity of a laser-stirred Bose-Einstein condensate",
abstract = "We study superfluidity of a cigar-shaped Bose-Einstein condensate by stirring it with a Gaussian potential oscillating back and forth along the axial dimension of the condensate, motivated by experiments of Raman et al. [Phys. Rev. Lett. 83, 2502 (1999)0031-900710.1103/PhysRevLett.83.2502]. Using classical-field simulations and perturbation theory, we examine the induced heating rate, based on the total energy of the system, as a function of the stirring velocity v. We identify the onset of dissipation by a sharply increasing heating rate above a velocity vc, which we define as the critical velocity. We show that vc is influenced by the oscillating motion, the strength of the stirrer, the temperature, and the inhomogeneous density of the cloud. This results in a vanishing vc for the parameters similar to the experiments, which is inconsistent with the measurement of nonzero vc. However, if the heating rate is based on the thermal fraction after a 100ms equilibration time, our simulation recovers the experimental observations. We demonstrate that this discrepancy is due to the slow relaxation of the stirred cloud and dipole mode excitation of the cloud.",
author = "Hannes Kiehn and Singh, {Vijay Pal} and Ludwig Mathey",
note = "Funding Information: This work was supported by the Deutsche Forschungsgemeinschaft in the framework of SFB 925 Project No. 170620586 and the excellence cluster Advanced Imaging of Matter, EXC 2056, Project No. 390715994. V.P.S. acknowledges funding from the Cluster of Excellence QuantumFrontiers, EXC 2123, Project No. 390837967.",
year = "2022",
month = apr,
day = "25",
doi = "10.48550/arXiv.2110.14634",
language = "English",
volume = "105",
journal = "Physical Review A",
issn = "2469-9926",
publisher = "American Physical Society",
number = "4",
}