| The description of bosons in disordered potentials requires from the outset the consideration of
their interaction. I will show that for low density $n$ a boson condensate decays into fragments. Increasing
$n$ the number of fragments increases untill at a critical density $n_c$ the transition to the superfluid proceeds.
$n_c$ is determine by the equality of the Larkin and the healing length.
Two applications of our theory will be considered: cold atoms in disordered traps and the insulating phase
of a disordered superconductors in an external magnetic field.
(see also Phys. Rev. B 80, 104515 (2009), Phys. Rev. Lett. 105, 267001 (2010)) |