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Title: Collective excitations of low-density fermion-boson quantum-liquid mixtures

Abstract

We investigate the collective excitations of a low-temperature dilute gas mixture that consists of a Bose-Einstein condensate (BEC) and a Fermi gas that is a normal (i.e., nonsuperfluid) Fermi liquid. We find that the BEC-mediated fermion-fermion interactions, as a consequence of retardation, can become repulsive and support a zero-sound mode that is essentially undamped. In addition, we find a damped zero-sound mode that can be described as a BEC sound mode modified by fermion-mediated boson-boson interactions, and we derive its decay rate caused by Landau damping. We study the mode structure of these excitations and find avoided-crossing behavior as well as a termination point. The collective-mode dynamics also reveals that phase separation sets in when the fermion-mediated boson-boson interaction destroys the stability of the homogeneous BEC. We estimate the time and length scales of the onset of the phase separation, and we discuss the feasibility of experimentally probing these consequences of mediated interactions.

Authors:
;  [1];  [2]
  1. ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA and Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20786547
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.72.053601; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BOSE-EINSTEIN CONDENSATION; BOSONS; COLLECTIVE EXCITATIONS; DECAY; DENSITY; FERMI GAS; FERMIONS; LANDAU DAMPING; LIQUIDS; MIXTURES; SOUND WAVES; STABILITY; ZERO SOUND

Citation Formats

Santamore, D. H., Timmermans, Eddy, and T-4, Theory division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Collective excitations of low-density fermion-boson quantum-liquid mixtures. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Santamore, D. H., Timmermans, Eddy, & T-4, Theory division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Collective excitations of low-density fermion-boson quantum-liquid mixtures. United States. doi:10.1103/PHYSREVA.72.0.
Santamore, D. H., Timmermans, Eddy, and T-4, Theory division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545. Tue . "Collective excitations of low-density fermion-boson quantum-liquid mixtures". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786547,
title = {Collective excitations of low-density fermion-boson quantum-liquid mixtures},
author = {Santamore, D. H. and Timmermans, Eddy and T-4, Theory division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545},
abstractNote = {We investigate the collective excitations of a low-temperature dilute gas mixture that consists of a Bose-Einstein condensate (BEC) and a Fermi gas that is a normal (i.e., nonsuperfluid) Fermi liquid. We find that the BEC-mediated fermion-fermion interactions, as a consequence of retardation, can become repulsive and support a zero-sound mode that is essentially undamped. In addition, we find a damped zero-sound mode that can be described as a BEC sound mode modified by fermion-mediated boson-boson interactions, and we derive its decay rate caused by Landau damping. We study the mode structure of these excitations and find avoided-crossing behavior as well as a termination point. The collective-mode dynamics also reveals that phase separation sets in when the fermion-mediated boson-boson interaction destroys the stability of the homogeneous BEC. We estimate the time and length scales of the onset of the phase separation, and we discuss the feasibility of experimentally probing these consequences of mediated interactions.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 5,
volume = 72,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}