Dynamical conductivity of the two-dimensional Bose condensate: Superfluid-insulator transition for a long-range random potential

Abstract

We calculate the dynamical conductivity of a disordered charged Bose condensate in two dimensions with a long-range random potential due to charged impurities with a large spacer width α. Analytical results for the frequency-dependent conductivity for weak disorder are derived. For strong disorder the frequency-dependent conductivity is given in terms of a transcendental equation. The disorder-induced transition from a superfluid phase to an insulator phase is discussed. The density-density relaxation function and the screening properties of the disordered Bose gas are calculated. Experimental results for high-Tc superconductors are discussed.