The superfluidity phenomenon: Is everything understood?
Patrick Navez
Ecole Polytechnique CP 165, Université Libre de Louvain, 50 av. F. D. Roosevelt, B-1050 Brussels, Belgium
We present the microscopic kinetic theory of a
homogeneous dilute Bose condensed gas in the generalized random phase
approximation (GRPA), which satisfies the following requirements:
1) the mass, momentum and energy conservation laws; 2)
the H-theorem; 3) the superfluidity property and 4)
the recovery of the Bogoliubov theory at zero temperature.
In this approach, the condensate influences
the binary collisional process between two normal atoms,
in the sense that
their interaction force results from the mediation of a Bogoliubov
collective excitation traveling throughout the condensate.
Furthermore, as long as the Bose gas is stable, no collision happens
between condensed and normal atoms. In this paper, we show how the
kinetic theory in the GRPA allows to calculate the dynamic structure
factor at finite temperature and when the normal and superfluid are
in a relative motion. The obtained spectrum for this factor provides
a prediction which, compared to the experimental results, allows to validate
the GRPA.
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