arXiv subjects

E. J. Torres-Herrera

Publications and source records attributed to E. J. Torres-Herrera.

22 records · Page 2Linked to original sources

arXiv2013

Time Fluctuations in Isolated Quantum Systems of Interacting Particles

Numerically, we study the time fluctuations of few-body observables after relaxation in isolated dynamical quantum systems of interacting particles. Our results suggest that they decay exponentially with system size in both regimes, integrable and chaotic. The integrable systems considered are solvable with the Bethe ansatz and have a highly nondegenerate spectrum. This is in contrast with integrable Hamiltonians mappable to noninteracting ones. We show that the coefficient of the exponential decay depends on the level of delocalization of the initial state with respect to the energy shell.

cond-mat.stat-mech↗

arXiv2013

Non-conventional Anderson localization in a matched quarter stack with metamaterials

We study the problem of non-conventional Anderson localization emerging in bilayer periodic-on-average structures with alternating layers of materials with positive and negative refraction indices $n_a$ and $n_b$. Main attention is paid to the model of the so-called quarter stack with perfectly matched layers (the same unperturbed by disorder impedances, $Z_a=Z_b$, and optical path lengths, $n_ad_a=|n_b| d_b$, with $d_a$, $d_b$ being the thicknesses of basic layers). As was recently numerically discovered, in such structures with weak fluctuations of refractive indices (compositional disorder) the localization length $L_{loc}$ is enormously large in comparison with the conventional localization occurring in the structures with positive refraction indices only. In this paper we develop a new approach which allows us to derive the expression for $L_{loc}$ for weak disorder and any wave frequency $ω$. In the limit $ω\rightarrow 0$ one gets a quite specific dependence, $L^{-1}_{loc}\proptoσ^4ω^8$ which is obtained within the fourth order of perturbation theory. We also analyze the interplay between two types of disorder, when in addition to the fluctuations of $n_a$, $n_b$ the thicknesses $d_a$, $d_b$ slightly fluctuate as well (positional disorder). We show how the conventional localization recovers with an addition of positional disorder.

cond-mat.dis-nn↗

arXiv2011

Non-Conventional Anderson Localization in Bilayered Structures with Metamaterials

We have developed an approach allowing us to resolve the problem of non-conventional Anderson localization emerging in bilayered periodic-on-average structures with alternating layers of right-handed and left-handed materials. Recently, it was numerically discovered that in such structures with weak fluctuations of refraction indices, the localization length $L_{loc}$ can be enormously large for small wave frequencies $ω$. Within the fourth order of perturbation theory in disorder, $σ^2 \ll 1$, we derive the expression for $L_{loc}$ valid for any $ω$. In the limit $ω\rightarrow 0$ one gets a quite specific dependence, $L^{-1}_{loc} \propto σ^4 ω^8$. Our approach allows one to establish the conditions under which this effect can be observed.

cond-mat.dis-nn↗

arXiv2011

Anderson Localization in Metamaterials with Compositional Disorder

The localization length has been derived for one-dimensional bi-layered structures with random perturbations in the refractive indices for each type of layers. Main attention is paid to the comparison between conventional materials and those consisting of mixed right-hand and left-hand materials. It is shown that the localization length is described by the universal expression for both cases. The analytical results are confirmed by numerical simulations.

cond-mat.dis-nn↗