INVESTIGADORES
CAPUZZI Pablo
congresos y reuniones científicas
Título:
Sound wave propagation in strongly elongated
fermion clouds at finite collisionality
Autor/es:
P. CAPUZZI; P. VIGNOLO; F. FEDERICI; M. P. TOSI
Lugar:
Cortona, Italia
Reunión:
Workshop; Third International Workshop on "Theory of Quantum Gases and Quantum Coherence"; 2005
Institución organizadora:
Scuola Normale Superiore, Pisa
Resumen:
We evaluate the transition from zero-sound to first-sound behaviour with
increasing collisionality in the propagation of density waves through an
ultracold gaseous mixture of fermionic atoms in the normal state confined
inside a cigar-shaped harmonic trap. We study for this purpose the evolution
of the one-body distribution functions associated with a density perturbation
generated in the central region of the cloud, as obtained by numerical solution
of the Vlasov–Landau equations. We examine a variety of trap anisotropies
and of repulsive or attractive interaction strengths between the components of
the mixture. The speed of propagation of the density disturbance is found to
decrease in both cases as the magnitude of the coupling strength is increased.
The results are compared with the values of the speed of zero sound and of first
sound, as obtained analytically from the limit of vanishing collisionality and
from linearized hydrodynamics. The main effects of the quasi-one-dimensional
confinement are the stabilization of zero-sound excitations in the attractive
regime before collapse and the lowering of the hydrodynamic sound velocity
by a factor sqrt(3/5) relative to three-dimensional behaviour.