148 research outputs found
Robustness of quantum discord to sudden death
We calculate the dissipative dynamics of two-qubit quantum discord under
Markovian environments. We analyze various dissipative channels such as
dephasing, depolarizing, and generalized amplitude damping, assuming
independent perturbation, in which each qubit is coupled to its own channel.
Choosing initial conditions that manifest the so-called sudden death of
entanglement, we compare the dynamics of entanglement with that of quantum
discord. We show that in all cases where entanglement suddenly disappears,
quantum discord vanishes only in the asymptotic limit, behaving similarly to
individual decoherence of the qubits, even at finite temperatures. Hence,
quantum discord is more robust than the entanglement against to decoherence so
that quantum algorithms based only on quantum discord correlations may be more
robust than those based on entanglement.Comment: 4 figures, 4 page
Non-Markovian Dynamics of Quantum Discord
We evaluate the quantum discord dynamics of two qubits in independent and
common non-Markovian environments. We compare the dynamics of entanglement with
that of quantum discord. For independent reservoirs the quantum discord
vanishes only at discrete instants whereas the entanglement can disappear
during a finite time interval. For a common reservoir, quantum discord and
entanglement can behave very differently with sudden birth of the former but
not of the latter. Furthermore, in this case the quantum discord dynamics
presents sudden changes in the derivative of its time evolution which is
evidenced by the presence of kinks in its behavior at discrete instants of
time.Comment: 6 pages, 4 figure
Purity as a witness for initial system-environment correlations in open-system dynamics
We study the dynamics of a two-level atom interacting with a Lorentzian
structured reservoir considering initial system-environment correlations. It is
shown that under strong system-reservoir coupling the dynamics of purity can
determine whether there are initial correlations between system and
environment. Moreover, we investigate the interaction of two two-level atoms
with the same reservoir. In this case, we show that besides determining if
there are initial system-environment correlations, the dynamics of the purity
of the atomic system allows the identification of the distinct correlated
initial states. In addition, the dynamics of quantum and classical correlations
is analyzed.Comment: 6 pages, 3 figure
Antimicrobial resistance in Escherichia coli and Enterococcus sp. isolated from swine carcasses at the pre-chill stage
The prevalence of antimicrobial resistant bacteria has been increasingly monitored in animals in order to prevent the spread of these strains through the food supply chain. Particularly, the emergence of vancomycin-resistant Enterococcus and Extended-spectrum beta-lactamases (ESBL) producing Enterobacteriaceae has been investigated worldwide. In the current study, the frequency of antimicrobial resistance of generic Escherichia coli and Enterococcus isolated from wine carcasses sampled at the pre-chill stage was assessed
Mean excitation numbers due to anti-rotating term (MENDART) in cavity QED under Lindbladian dephasing
We study the photon generation from arbitrary initial state in cavity QED due
to the combined action of the anti-rotating term present in the Rabi
Hamiltonian and Lindblad-type dephasing. We obtain a simple set of differential
equations describing this process and deduce useful formulae for the moments of
the photon number operator, demonstrating analytically that the average photon
number increases linearly with time in the asymptotic limit.Comment: 4 page
Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED
We present a way to engineer an effective anti-Jaynes-Cumming and a
Jaynes-Cumming interaction between an atomic system and a single cavity mode
and show how to employ it in reservoir engineering processes. To construct the
effective Hamiltonian, we analyse considered the interaction of an atomic
system in a \{Lambda} configuration, driven by classical fields, with a single
cavity mode. With this interaction, we firstly show how to generate a
decoherence-free displaced squeezed state for the cavity field. In our scheme,
an atomic beam works as a reservoir for the radiation field trapped inside the
cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401
(2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in
high-Q resonators. In our scheme, all the atoms have to be prepared in the
ground state and, as in the cited article, neither atomic detection nor precise
interaction times between the atoms and the cavity mode are required. From this
same interaction, we can also generate an ideal squeezed reservoir for atomic
systems. For this purpose we have to assume, besides the engineered atom-field
interaction, a strong decay of the cavity field (i.e., the cavity decay must be
much stronger than the effective atom-field coupling). With this scheme, some
interesting effects in the dynamics of an atom in a squeezed reservoir could be
tested
Parâmetros microbiológicos de carcaças suínas amostradas na etapa de pré-resfriamento.
Projeto/Plano de Ação: 11.11.11.111
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