Delocalization in continuous disordered systems

Continuous one-dimensional models supporting extended states are studied. These delocalized states occur at well-defined values of the energy and are consequences of simple statistical correlation rules. We explicitly study alloys of δ-barrier potentials as well as alloys and liquids of quantum wells. The divergence of the localization length is studied and a critical exponent is found for the δ-barrier case, whereas for the quantum wells we find an exponent of 2 or depending on the wellșs parameters. These results support the idea that correlations between random scattering sequences break Anderson localization. We further calculate the conductance of disordered superlattices. At the peak transmission the relative fluctuations of the transmission coefficient are vanishing.