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Title

Collisionless and hydrodynamic excitations of trapped boson-fermion mixtures

Author(s)

Liu, Xia-Ji;  Hu, Hui

Abstract

Within a scaling ansatz formalism plus Thomas-Fermi approximation, we investigate the collective excitations of a harmonically trapped boson-fermion mixture in the collisionless and hydrodynamic limit at low temperature. Both the monopole and quadrupole modes are considered in the presence of spherical as well as cylindrically symmetric traps. In the spherical traps, the frequency of the monopole mode coincides in the collisionless and hydrodynamic regime, suggesting that it might be undamped in all collisional regimes. In contrast, for the quadrupole mode, the frequency differs largely in these two limits. In particular, we find that in the hydrodynamic regime the quadrupole oscillations with equal bosonic and fermionic amplitudes generate an exact eigenstate of the system, regardless of the boson-fermion interaction. This resembles the Kohn mode for the dipole excitation. We discuss in some detail the behavior of monopole and quadrupole modes as a function of boson-fermion coupling at different boson-boson interaction strength. Analytic solutions valid at weak and medium fermion-boson coupling are also derived and discussed.

Publication type

Journal article

Source

Physical Review A: Atomic, Molecular, and Optical Physics, Vol. 67, no. 2 (Feb 2003), article no. 023613

Publication year

2003

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0204 Condensed Matter Physics;  0205 Optical Physics

Keyword(s)

Approximation theory;  Bose-Einstein condensation;  Boson-fermion mixtures;  Condensation;  Differential equations;  Equations of motion;  Fermi gas;  Fermi level;  Fermions;  Hydrodynamics;  Kinetic theory;  Natural frequencies;  Oscillations;  Temperature;  Thomas-Fermi approximation

Publisher

American Physical Society

ISSN

1050-2947

Publisher URL

http://dx.doi.org/10.1103/PhysRevA.67.023613

Copyright

Copyright © 2003 The American Physical Society. The accepted manuscript of the paper is reproduced here for noncommerical purposes only in accordance with the copyright policy of the publisher.

Full text

Peer reviewed