چکیده : 

We present a theoretical study of the superfluidity and the corresponding

collective modes in two-component atomic Fermi gases

with s-wave attraction and synthetic Rashba spin–orbit coupling.

The general effective action for the collective modes is derived from

the functional path integral formalism. By tuning the spin–orbit

coupling from weak to strong, the system undergoes a crossover

from an ordinary BCS/BEC superfluid to a Bose–Einstein condensate

of rashbons. We show that the properties of the superfluid density

and the Anderson–Bogoliubov mode manifest this crossover.

At large spin–orbit coupling, the superfluid density and the sound

velocity become independent of the strength of the s-wave attraction.

The two-body interaction among the rashbons is also determined.

When a Zeeman field is turned on, the system undergoes

quantum phase transitions to some exotic superfluid phases which

are topologically nontrivial. For the two-dimensional system, the

nonanalyticities of the thermodynamic functions and the sound