739 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
Functional characterization of generalized Langevin equations
We present an exact functional formalism to deal with linear Langevin
equations with arbitrary memory kernels and driven by any noise structure
characterized through its characteristic functional. No others hypothesis are
assumed over the noise, neither the fluctuation dissipation theorem. We found
that the characteristic functional of the linear process can be expressed in
terms of noise's functional and the Green function of the deterministic
(memory-like) dissipative dynamics. This object allow us to get a procedure to
calculate all the Kolmogorov hierarchy of the non-Markov process. As examples
we have characterized through the 1-time probability a noise-induced interplay
between the dissipative dynamics and the structure of different noises.
Conditions that lead to non-Gaussian statistics and distributions with long
tails are analyzed. The introduction of arbitrary fluctuations in fractional
Langevin equations have also been pointed out
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
Observing the evaporation transition in vibro-fluidized granular matter
By shaking a sand box the grains on the top start to jump giving the picture
of evaporating a sand bulk, and a gaseous transition starts at the surface
granular matter (GM) bed. Moreover the mixture of the grains in the whole bed
starts to move in a cooperative way which is far away from a Brownian
description. In a previous work we have shown that the key element to describe
the statistics of this behavior is the exclusion of volume principle, whereby
the system obeys a Fermi configurational approach. Even though the experiment
involves an archetypal non-equilibrium system, we succeeded in defining a
global temperature, as the quantity associated to the Lagrange parameter in a
maximum entropic statistical description. In fact in order to close our
approach we had to generalize the equipartition theorem for dissipative
systems. Therefore we postulated, found and measured a fundamental dissipative
parameter, written in terms of pumping and gravitational energies, linking the
configurational entropy to the collective response for the expansion of the
centre of mass (c.m.) of the granular bed. Here we present a kinetic approach
to describe the experimental velocity distribution function (VDF) of this
non-Maxwellian gas of macroscopic Fermi-like particles (mFp). The evaporation
transition occurs mainly by jumping balls governed by the excluded volume
principle. Surprisingly in the whole range of low temperatures that we measured
this description reveals a lattice-gas, leading to a packing factor, which is
independent of the external parameters. In addition we measure the mean free
path, as a function of the driving frequency, and corroborate our prediction
from the present kinetic theory.Comment: 6 pages, 4 figures, submitted for publication September 1st, 200
FTIR-ATR detection method for emerging C3-plants-derivated adulterants in honey: Beet, dates, and carob syrups
The European Union Publications Office has recently presented a report on the European Union's coordinated action with the Joint Research Centre to determine certain fraudulent practices in the honey sector, in which it has been indicated that 74% of the samples analyzed, imported from China, and 93% of the samples analyzed, imported from Turkey, the two largest honey producers worldwide, presented at least one indicator of exogenous sugar or suspicion of being adulterated. This situation has revealed the critical state of the problem of honey adulteration worldwide and the need to develop analytical techniques for its detection. Even though the adulteration of honey is carried out in a general way with sweetened syrups derived from C4 plants, recent studies have indicated the emerging use of syrups derived from C3 plants for the adulteration of honey. This kind of adulteration makes it impossible to analyze its detection using official analysis techniques. In this work, we have developed a fast, simple, and economical method based on the Fourier transform infrared spectroscopy technique, with attenuated total reflectance, for the qualitative, quantitative, and simultaneous determination of beetroot, date, and carob syrups, derived from of C3 plants; whose available bibliography is very scarce and analytically not very conclusive for its use by the authorities. The proposed method has been based on the establishment of the spectral differences between honey and the mentioned syrups at eight different points in the spectral region between 1200 and 900 cm-1 of the mid-infrared, characteristic of the vibrational modes of carbohydrates in honey, which allows the pre-discrimination of the presence or absence of the syrups studied, and their subsequent quantification, with precision levels lower than 2.0% of the relative standard deviation and relative errors lower than 2.0% (m/m).S
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