Measurement of the Dynamical Structure Factor of a 1D Interacting Fermi Gas

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Measurement of the Dynamical Structure Factor of a 1D Interacting Fermi Gas

T. L. Yang, P. Grišins, Y. T. Chang, Z. H. Zhao, C. Y. Shih, T. Giamarchi, and R. G. Hulet

Phys. Rev. Lett. 121, 103001 – Published 4 September 2018

Abstract

We present measurements of the dynamical structure factor $S (q, ω)$ of an interacting one-dimensional Fermi gas for small excitation energies. We use the two lowest hyperfine levels of the ${}^{6}{Li}$ atom to form a pseudospin- $1 / 2$ system whose $s$ -wave interactions are tunable via a Feshbach resonance. The atoms are confined to one dimension by a two-dimensional optical lattice. Bragg spectroscopy is used to measure a response of the gas to density (“charge”) mode excitations at a momentum $q$ and frequency $ω$ , as a function of the interaction strength. The spectrum is obtained by varying $ω$ , while the angle between two laser beams determines $q$ , which is fixed to be less than the Fermi momentum $k_{F}$ . The measurements agree well with Tomonaga-Luttinger theory.

Received 16 March 2018
Revised 14 May 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.103001

Physics Subject Headings (PhySH)

Cold gases in optical lattices Fermi gases Fermions Quasiparticles & collective excitations

1-dimensional systems Collective dynamics

Atomic, Molecular & OpticalCondensed Matter, Materials & Applied Physics

Authors & Affiliations

T. L. Yang¹, P. Grišins², Y. T. Chang¹, Z. H. Zhao¹, C. Y. Shih¹, T. Giamarchi², and R. G. Hulet¹

¹Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
²Department of Quantum Matter Physics, University of Geneva, 1211 Genève, Switzerland