Collisional oscillations of trapped boson-fermion mixtures in the approach to the collapse instability

Journal Article · Sat May 01 04:00:00 EDT 2004 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.69.053615· OSTI ID:20643660

Capuzzi, P; Minguzzi, A; Tosi, M P ^[1]

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1. NEST-INFM and Classe di Scienze, Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)

We study the collective modes of a confined gaseous cloud of bosons and fermions with mutual attractive interactions at zero temperature. The cloud consists of a Bose-Einstein condensate and a spin-polarized Fermi gas inside a spherical harmonic trap and the coupling between the two species is varied by increasing either the magnitude of the interspecies s-wave scattering length or the number of bosons. The mode frequencies are obtained in the collisional regime by solving the equations of generalized hydrodynamics and are compared with the spectra calculated in the collisionless regime within a random-phase approximation. We find that, as the mixture is driven towards the collapse instability, the frequencies of the modes of fermionic origin show a blue shift which can become very significant for large numbers of bosons. Instead the modes of bosonic origin show a softening, which becomes most pronounced in the very proximity of collapse. Explicit illustrations of these trends are given for the monopolar spectra, but similar trends are found for the dipolar and quadrupolar spectra except for the surface (n=0) modes which are essentially unaffected by the interactions.

• OSTI ID: 20643660
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 5 Vol. 69; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
BOSE-EINSTEIN CONDENSATION
BOSONS
COLLISIONS
COUPLING
FERMI GAS
FERMIONS
HYDRODYNAMICS
INSTABILITY
MIXTURES
OSCILLATIONS
RANDOM PHASE APPROXIMATION
S WAVES
SCATTERING
SCATTERING LENGTHS
SPECTRAL SHIFT
SPHERICAL CONFIGURATION
SPIN
SURFACES
TRAPPING
TRAPS