10,289 research outputs found
Overcoming ambiguities in classical and quantum correlation measures
We identify ambiguities in the available frameworks for defining quantum,
classical, and total correlations as measured by discordlike quantifiers. More
specifically, we determine situations for which either classical or quantum
correlations are not uniquely defined due to degeneracies arising from the
optimization procedure over the state space. In order to remove such
degeneracies, we introduce a general approach where correlations are
independently defined, escaping therefore from a degenerate subspace. As an
illustration, we analyze the trace-norm geometric quantum discord for two-qubit
Bell-diagonal states.Comment: 5 pages, 2 figures. v2: Minor corrections. Published versio
Geometric classical and total correlations via trace distance
We introduce the concepts of geometric classical and total correlations
through Schatten 1-norm (trace norm), which is the only Schatten p-norm able to
ensure a well-defined geometric measure of correlations. In particular, we
derive the analytical expressions for the case of two-qubit Bell-diagonal
states, discussing the superadditivity of geometric correlations. As an
illustration, we compare our results with the entropic correlations, discussing
both their hierarchy and monotonicity properties. Moreover, we apply the
geometric correlations to investigate the ground state of spin chains in the
thermodynamic limit. In contrast to the entropic quantifiers, we show that the
classical correlation is the only source of 1-norm geometric correlation that
is able to signaling an infinite-order quantum phase transition.Comment: v2: published versio
Non-Markovianity through entropy-based quantum thermodynamics
We introduce a generalized approach to characterize the non-Markovianity of
quantum dynamical maps via breakdown of monotonicity of thermodynamic
functions. By adopting an entropy-based formulation of quantum thermodynamics,
we use the relationship between heat and entropy to propose a measure of
non-Markovianity based on the heat flow for single-qubit quantum evolutions.
This measure can be applied for unital dynamical maps that do not invert the
sign of the internal energy. Under certain conditions, it can also be extended
for other thermodynamic functions, such as internal energy and work flows. In
this context, a natural connection between heat and quantum coherence can be
identified for dynamical maps that are both unital and incoherent. As
applications, we explore dissipative and non-dissipative quantum dynamical
processes, illustrating the compatibility between our thermodynamic quantifiers
and the well-establish measure defined via quantum coherence.Comment: 7 pages, 3 figure
COMPARISON ANALYSIS OF CORRELATIONS FOR INTERFACIAL FRICTION FACTOR APPLIED IN GAS-LIQUID ANNULAR FLOW IN VERTICAL PIPES
Gas-liquid flows in pipes can occur in the form of an annular pattern in which the liquid flows as a thin film at pipe wall and the gas flows as a core in pipe center. This flow pattern is often encountered at boiling and condensation processes, for example, in industries of steam generation, cooling or petroleum. In annular flow, the interfacial friction factor is one of the important closing parameters for the definition of the interfacial shear stress and consequently the pressure gradient. In the literature, several correlations are found to estimate the interfacial friction factor. The main objective of this work is to carry out a comparative analysis of some these correlations against experimental data also obtained from the literature. The features and limitations of each correlation were observed, as well as the accuracy of each in relation to experimental data. The results obtained demonstrate that correlations analyzed, present relatively satisfactory results, despite the different characteristics of the correlations, however, it is necessary to carry out more extensive analyses involving others correlations and sets of experimental data
Estabilidade de agregados em solos sódicos e salino-sódicos.
bitstream/item/36226/1/Estabilidade-de-Agregados.pd
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