Three attractively interacting fermions in a harmonic trap: exact solution, ferromagnetism, and high-temperature thermodynamics

Search Swinburne Research Bank

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/91581

Download PDF (Published version) (Adobe Acrobat PDF, -1 bytes)

Title: Three attractively interacting fermions in a harmonic trap: exact solution, ferromagnetism, and high-temperature thermodynamics
Author(s): Liu, Xia-Ji; Hu, Hui; Drummond, Peter D.
Abstract: Three fermions with strongly repulsive interactions in a spherical harmonic trap constitute the simplest nontrivial system that can exhibit the onset of itinerant ferromagnetism. Here, we present exact solutions for three trapped, attractively interacting fermions near a Feshbach resonance. We analyze energy levels on the upper branch of the resonance where the atomic interaction is effectively repulsive. When the s-wave scattering length a is sufficiently positive, three fully polarized fermions are energetically stable against a single spin-flip, indicating the possibility of itinerant ferromagnetism, as inferred in the recent experiment. We also investigate the high-temperature thermodynamics of a strongly repulsive or attractive Fermi gas using a quantum virial expansion. The second and third virial coefficients are calculated. The resulting equations of state can be tested in future quantitative experimental measurements at high temperatures and can provide a useful benchmark for quantum Monte Carlo simulations.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Engineering and Industrial Sciences. Centre for Atom Optics and Ultrafast Spectroscopy. ARC Centre of Excellence for Quantum-Atom Optics
Source: Physical Review A: Atomic, Molecular, and Optical Physics, Vol. 82, no. 2 (Aug 2010), article no. 023619
Publication year: 2010
FOR Code(s): 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0204 Condensed Matter Physics; 0205 Optical Physics
Keyword(s): Fermi gas; Ferromagnetism; Monte Carlo simulations
Publisher: American Physical Society
ISSN: 1050-2947
Publisher URL: http://dx.doi.org/10.1103/PhysRevA.82.023619
Research Projects: Ultracold atomic Fermi gases in the strongly interacting regime: a new frontier of quantum many-body physics, Australian Research Council grant number DP0984522
Imbalanced superfluidity: the quantum mystery that defies solution, Australian Research Project grant number DP0984637
Additional information: This article was highlighted by the American Physical Society's series 'Physics: spotlighting exceptional research'. See: http://dx.doi.org/10.1103/Physics.3.74.
Full text
Peer reviewed