Metal-insulator transition induced by random dipoles

Abstract

Cataloged from PDF version of article.We study the localization properties of a test dipole feeling the disordered potential induced by dipolar impurities trapped at random positions in an optical lattice. This random potential is marked by correlations which are a convolution of short-range and long-range ones. We show that when short-range correlations are dominant, extended states can appear in the spectrum. Introducing long-range correlations, the extended states, if any, are wiped out and localization is restored over the whole spectrum. Moreover, long-range correlations can either increase or decrease the localization length at the center of the band, which indicates a richer behavior than previously predicted

Quantum boomerang effect: beyond the standard Anderson model

“…For b > 3, however, numerical data suggest that the spatial extension of the wavepacket in the localized regime grows with b. To understand the behavior of x 2 (t) for small values of b, we numerically computed the inverse localization length for the model ( 15), using the identity [28,29]…”

Density wave propagation in a two-dimensional random dimer potential: From a single to a bipartite square lattice

“…The fact that the impurities cannot be next-neighbours introduces short-range correlations in the disorder. Such a potential could be realized by dipolar impurities pinned at the minima of a lattice potential [24]. If the percentage p of impurities is zero, the lattice is MP with site energies equal to 0 and all hopping parameters equal to t (left panel of Fig.…”

“…Moreover, for weakly interacting systems, correlated disorder can shift the onset of superfluidity [18][19][20][21], or enhance superfluidity itself, even in the presence of strong disorder [6]. This has been shown for the twodimensional Dual Random Dimer Model (2D-DRDM) [6], that, analogously to the well-known one-dimensional (1D) model [22][23][24], is a tight-binding model characterized by correlated impurities that become "transparent"at a given resonance energy, like identical Fabry-Perot cavities. If the Hamiltonian parameters are tuned * Electronic address: capuzzi@df.uba.ar † Electronic address: Patrizia.Vignolo@inphyni.cnrs.fr so that the resonance energy matches the ground-state energy, the ground state is not affected by the disorder, even in the presence of weak interactions.…”

“…This happens at the ground-state energy, but, as soon as the system is perturbed, higher energy states are involved, and it is not straightforward to derive the response of the system. Indeed, strictlyspeaking, the resonant energy in the absence of interactions is only one (or few [24]), so that all the other states with different energy should be localized, even if a part of them (N 1/2 in 1D, N being the number of states [22]) is expected to be localized on the entire system length.…”

Enhancing quantum coherence with short-range correlated disorder

“…In the absence of interactions, if the impurity distribution is completely random, all states of the spectrum are exponentially localized in dimensions one (1D) and two (2D), while a mobility edge exists in dimensions three (3D) [1][2][3]. If the impurity positions are correlated, as for instance if it exists a minimum distance between the impurities [4,5], some delocalized states can appear in the spectrum. This was demonstrated in 1D in the context of the Random Dimer Model (RDM) and of the Dual Random Dimer Model (DRDM) [6].…”