Bose-Einstein condensation in quasi-2D trapped gases

We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature T_c the equilibrium state is a true condensate, whereas at intermediate temperatures T<T_c one has a quasicondensate (condensate with fluctuating phase). The mean-field interaction in a quasi-2D gas is sensitive to the frequency w₀ of the (tight) confinement in the "frozen" direction, and one can switch the sign of the interaction by changing w₀. Variation of w₀ can also reduce the rates of inelastic processes. This offers promising prospects for tunable BEC in trapped quasi-2D gases.