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Title

Universal dynamic structure factor of a strongly correlated Fermi gas

Author(s)

Hu, Hui;  Liu, Xia-Ji

Abstract

Universality of strongly interacting fermions is a topic of great interest in diverse fields. Here we investigate theoretically the universal dynamic density response of resonantly interacting ultracold Fermi atoms in the limit of either high temperature or large frequency. At high temperature, we use quantum virial expansion to derive universal, nonperturbative expansion functions of the dynamic structure factor; at large momentum, we conjecture that the second-order expansion function gives the Wilson coefficient used in the operator product expansion method. The dynamic structure factor is therefore determined by its second-order expansion function with an overall normalization factor given by Tan's [ S. Tan Ann. Phys. (NY) 323 2952 (2008); S. Tan Ann. Phys. (NY) 323 2971 (2008); S. Tan Ann. Phys. (NY) 323 2987 (2008)] contact parameter. We show that the spin-parallel and antiparallel dynamic structure factors have, respectively, a tail of the form ∼±ω−5/2 for ω→∞, decaying slower than the total dynamic structure factor found previously (∼ω−7/2). Our predictions for the dynamic structure factor at high temperature or large frequency are testable using Bragg spectroscopy for ultracold atomic Fermi gases.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Engineering and Industrial Sciences. Centre for Atom Optics and Ultrafast Spectroscopy

Source

Physical Review A: Atomic, Molecular, and Optical Physics, Vol. 85, no. 2 (Feb 2012), article no. 023612

Publication year

2012

FOR Code(s)

01 Mathematical Sciences;  02 Physical Sciences;  03 Chemical Sciences

Keyword(s)

Dynamic structure factor;  Fermi gases;  Virial expansion

Publisher

American Physical Society

ISSN

1050-2947

Publisher URL

http://dx.doi.org/10.1103/PhysRevA.85.023612

Copyright

Copyright © 2012 American Physical Society. The published version is reproduced with the kind permission of the publisher.

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

Full text

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