30 research outputs found
Bath-induced correlations in an infinite-dimensional Hilbert space
Quantum correlations between two free spinless dissipative distinguishable
particles (interacting with a thermal bath) are studied analytically using the
quantum master equation and tools of quantum information. Bath-induced
coherence and correlations in an infinite-dimensional Hilbert space are shown.
We show that for temperature T > 0 the time-evolution of the reduced density
matrix cannot be written as the direct product of two independent particles. We
have found a time-scale that characterizes the time when the bath-induced
coherence is maximum before being wiped out by dissipation (purity, relative
entropy, spatial dispersion, and mirror correlations are studied). The Wigner
function associated to the Wannier lattice (where the dissipative quantum walks
move) is studied as an indirect measure of the induced correlations among
particles. We have supported the quantum character of the correlations by
analyzing the geometric quantum discord.Comment: 13 pages, 5 figures. arXiv admin note: substantial text overlap with
arXiv:1512.0870
Quantum correlations in nanostructured two-impurity Kondo systems
We study the ground-state entanglement properties of nanostructured Kondo
systems consisting of a pair of impurity spins coupled to a background of
confined electrons. The competition between the RKKY-like coupling and the
Kondo effect determines the development of quantum correlations between the
different parts of the system. A key element is the electronic filling due to
confinement. An even electronic filling leads to results similar to those found
previously for extended systems, where the properties of the reduced
impurity-spin subsystem are uniquely determined by the spin correlation
function defining a one-dimensional phase space. An odd filling, instead,
breaks spin-rotation symmetry unfolding a two-dimensional phase space showing
rich entanglement characteristics as, e.g., the requirement of a larger amount
of entanglement for the development of non-local correlations between impurity
spins. We check these results by numerical simulations of elliptic quantum
corrals with magnetic impurities at the foci as a case study.Comment: Submitted for publication. 8 pages, 4 figures. Revised versio
Dynamics of indistinguishable free particles driven by a quantum bath
Time evolution of correlations for two indistinguishable free particles, in a one-dimensional lattice interacting with a quantum bath have been studied in the Born-Markov approximation. The analytical solution for the density matrix is obtained, for bosons and fermions, in the second quantization formalism. Time-evolution of the negativity of indistinguishable particles is analyzed for quantum mixed states. Quantum correlations heavily depend on the selected bipartition, in return, a small difference between the statistics of the particles have been noted, due to the Pauli exclusion principle. In the presence of the dissipation, the negativity (a non-classical correlation) shows a time-oscillatory behavior for a particular geometrical bipartition. The total probability of finding one particle in each subsystem has also been calculated showing a consistent behavior.Fil: Nizama Mendoza, Marco Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Física; ArgentinaFil: Caceres Garcia Faure, Manuel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin
Penetration of waves in global stochastic conducting media
The attenuation in the propagation of a plane wave in conducting media has been studied. We analyzed a wave motion suffering dissipation by the Joule effect in its propagation in a medium with global disorder. We solved the stochastic telegrapher’s equation in the Fourier-Laplace representation allowing us to find the space penetration length of a plane wave in a complex conducting medium. Considering fluctuations in the loss of energy, we found a critical value kc for Fourier’s modes, thus if |k| < kc the waves are localized. We showed that the penetration length is inversely proportional to kc. Thus, the penetration length L = k−1 c becomes an important piece of information for describing wave propagation with Markovian and non-Markovian fluctuations in the rate of the absorption of energy τ −1. In addition, intermittent fluctuations in this rate have also been studied.Fil: Nizama Mendoza, Marco Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Física; ArgentinaFil: Caceres Garcia Faure, Manuel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro | Universidad Nacional de Cuyo. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro; Argentin
Fisher and Shannon Functionals for Hyperbolic Diffusion
The complexity measure for the distribution in space-time of a finite-velocity diffusionprocess is calculated. Numerical results are presented for the calculation of Fisher’s information,Shannon’s entropy, and the Cramér–Rao inequality, all of which are associated with a positivelynormalized solution to the telegrapher’s equation. In the framework of hyperbolic diffusion, thenon-local Fisher’s information with the x-parameter is related to the local Fisher’s information with thet-parameter. A perturbation theory is presented to calculate Shannon’s entropy of the telegrapher’sequation at long times, as well as a toy model to describe the system as an attenuated wave in theballistic regime (short times).Fil: Cáceres, Manuel O.. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Nizama Mendoza, Marco Alfredo. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pennini, Flavia Catalina. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin
Emergence of stationary multimodality under two-timescaled dichotomic noise
We study a linear Langevin dynamics driven by an additive non-Markovian symmetrical dichotomic noise. It is shown that when the statistics of the time intervals between noise transitions is characterized by two well differentiated timescales, the stationary distribution may develop multimodality (bi- and trimodality). The underlying effects that lead to a probability concentration in different points include intermittence and also a dynamical locking of realizations. Our results are supported by numerical simulations as well as by an exact treatment obtained from a Markovian embedding of the full dynamics, which leads to a third-order differential equation for the stationary distribution.Fil: Budini, Adrian Adolfo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Mc Hardy, Isaias. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Nizama Mendoza, Marco Alfredo. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Caceres Garcia Faure, Manuel Osvaldo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin
Non-equilibrium transition from dissipative quantum walk to classical random walk
We have investigated the time-evolution of a free particle in interaction
with a phonon thermal bath, using the tight-binding approach. A dissipative
quantum walk can be defined and many important non-equilibrium decoherence
properties can be investigated analytically. The non-equilibrium statistics of
a pure initial state have been studied. Our theoretical results indicate that
the evolving wave-packet shows the suppression of Anderson's boundaries
(ballistic peaks) by the presence of dissipation. Many important relaxation
properties can be studied quantitatively, such as von Neumann's entropy and
quantum purity. In addition, we have studied Wigner's function. The
time-dependent behavior of the quantum entanglement between a free particle -in
the lattice- and the phonon bath has been characterized analytically. This
result strongly suggests the non-trivial time-dependence of the off-diagonal
elements of the reduced density matrix of the system. We have established a
connection between the quantum decoherence and the dissipative parameter
arising from interaction with the phonon bath. The time-dependent behavior of
quantum correlations has also been pointed out, showing continuous transition
from quantum random walk to classical random walk, when dissipation increases.Comment: Submitted for publication. 17 pages, 6 figure