  When a system of spinless fermions in a disordered mesoscopic ring becomes
instable between the inhomogeneous configuration driven by the random potential
(Anderson insulator) and the homogeneous one driven by repulsive interactions
(Mott insulator), the persistent current can be enhanced by orders of
magnitude. This is illustrated by a study of the change of the ground state
energy under twisted boundary conditions using the density matrix
renormalization group algorithm.
