4,639 research outputs found
Information theory of quantum systems with some hydrogenic applications
The information-theoretic representation of quantum systems, which
complements the familiar energy description of the density-functional and
wave-function-based theories, is here discussed. According to it, the internal
disorder of the quantum-mechanical non-relativistic systems can be quantified
by various single (Fisher information, Shannon entropy) and composite (e.g.
Cramer-Rao, LMC shape and Fisher-Shannon complexity) functionals of the
Schr\"odinger probability density. First, we examine these concepts and its
application to quantum systems with central potentials. Then, we calculate
these measures for hydrogenic systems, emphasizing their predictive power for
various physical phenomena. Finally, some recent open problems are pointed out.Comment: 9 pages, 3 figure
Relativistic Klein-Gordon charge effects by information-theoretic measures
The charge spreading of ground and excited states of Klein-Gordon particles
moving in a Coulomb potential is quantitatively analyzed by means of the
ordinary moments and the Heisenberg measure as well as by use of the most
relevant information-theoretic measures of global (Shannon entropic power) and
local (Fisher's information) types. The dependence of these complementary
quantities on the nuclear charge Z and the quantum numbers characterizing the
physical states is carefully discussed. The comparison of the relativistic
Klein-Gordon and non-relativistic Schrodinger values is made. The
non-relativistic limits at large principal quantum number n and for small
values of Z are also reached.Comment: Accepted in New Journal of Physic
Three strongly correlated charged bosons in a one-dimensional harmonic trap: natural orbital occupancies
We study a one-dimensional system composed of three charged bosons confined
in an external harmonic potential. More precisely, we investigate the
ground-state correlation properties of the system, paying particular attention
to the strong-interaction limit. We explain for the first time the nature of
the degeneracies appearing in this limit in the spectrum of the reduced density
matrix. An explicit representation of the asymptotic natural orbitals and their
occupancies is given in terms of some integral equations.Comment: 6 pages, 4 figures, To appear in European Physical Journal
CP Violation and Family Mixing in the Effective Electroweak Lagrangian
We construct the most general effective Lagrangian of the matter sector of
the Standard Model, including mixing and CP violating terms. The Lagrangian
contains the effective operators that give the leading contribution in theories
where the physics beyond the Standard Model shows at a scale .
We perform the diagonalization and passage to the physical basis in full
generality. We determine the contribution to the different observables and
discuss the possible new sources of CP violation, the idea being to be able to
gain some knowledge about new physics beyond the Standard Model from general
considerations, without having to compute model by model. The values of the
coefficients of the effective Lagrangian in some theories, including the
Standard Model, are presented and we try to draw some general conclusions about
the general pattern exhibited by physics beyond the Standard Model in what
concerns CP violation. In the process we have had to deal with two theoretical
problems which are very interesting in their own: the renormalization of the
CKM matrix elements and the wave function renormalization in the on-shell
scheme when mixing is present.Comment: A misplaced sentence was correcte
Superconductivity induced by inter-band nesting in the three-dimensional honeycomb lattice
In order to study whether the inter-band nesting can favor superconductivity
arising from electron-electron repulsion in a three-dimensional system, we have
looked at the repulsive Hubbard model on a stack of honeycomb (i.e.,
non-Bravais) lattices with the FLEX method, partly motivated by the
superconductivity observed in MgB2. By systematically changing the shape of
Fermi surface with varied band filling n and the third-direction hopping, we
have found that the pair scattering across the two-bands is indeed found to
give rise to gap functions that change sign across the bands and behave as an
s- or d-wave within each band. This implies (a) the electron repulsion can
assist gapful pairing when a phonon-mechanism pairing exists, and (b) the
electron repulsion alone, when strong enough, can give rise to a d-wave-like
pairing, which should be, for a group-theoretic reason, a time-reversal broken
d+id with point nodes in the gap
The unexplored role of sedentary time and physical activity in glucose and lipid metabolism-related placental mRNAs in pregnant women who are obese: the DALI lifestyle randomised controlled trial
Objective: We aimed to explore: (i) the association of sedentary time (ST) and physical activity (PA) during pregnancy with the placental expression of genes related to glucose and lipid metabolism in pregnant women who are obese; (ii) maternal metabolic factors mediating changes in these placental transcripts; and (iii) cord blood markers related to the mRNAs mediating neonatal adiposity. Design: Multicentre randomised controlled trial. Setting: Hospitals in nine European countries. Population: A cohort of 112 pregnant women with placental tissue. Methods: Both ST and moderate-to-vigorous PA (MVPA) levels were measured objectively using accelerometry at three time periods during pregnancy. Main outcome measures: Placental mRNAs (FATP2, FATP3, FABP4, GLUT1 and PPAR-γ) were measured with NanoString technology. Maternal and fetal metabolic markers and neonatal adiposity were assessed. Results: Longer periods of ST, especially in early to middle pregnancy, was associated with lower placental FATP2 and FATP3 expression (P \u3c 0.05), whereas MVPA at baseline was inversely associated with GLUT1 mRNA (P = 0.02). Although placental FATP2 and FATP3 expression were regulated by the insulin–glucose axis (P \u3c 0.05), no maternal metabolic marker mediated the association of ST/MVPA with placental mRNAs (P \u3e 0.05). Additionally, placental FATP2 expression was inversely associated with cord blood triglycerides and free fatty acids (FFAs; P \u3c 0.01). No cord blood marker mediated neonatal adiposity except for cord blood leptin, which mediated the effects of PPAR-γ on neonatal sum of skinfolds (P \u3c 0.05). Conclusions: In early to middle pregnancy, ST is associated with the expression of placental genes linked to lipid transport. PA is hardly related to transporter mRNAs. Strategies aimed at reducing sedentary behaviour during pregnancy could modulate placental gene expression, which may help to prevent unfavourable fetal and maternal pregnancy outcomes. Tweetable abstract: Reducing sedentary behaviour in pregnancy might modulate placental expression of genes related to lipid metabolism in women who are obese
Additivity and non-additivity of multipartite entanglement measures
We study the additivity property of three multipartite entanglement measures,
i.e. the geometric measure of entanglement (GM), the relative entropy of
entanglement and the logarithmic global robustness. First, we show the
additivity of GM of multipartite states with real and non-negative entries in
the computational basis. Many states of experimental and theoretical interests
have this property, e.g. Bell diagonal states, maximally correlated generalized
Bell diagonal states, generalized Dicke states, the Smolin state, and the
generalization of D\"{u}r's multipartite bound entangled states. We also prove
the additivity of other two measures for some of these examples. Second, we
show the non-additivity of GM of all antisymmetric states of three or more
parties, and provide a unified explanation of the non-additivity of the three
measures of the antisymmetric projector states. In particular, we derive
analytical formulae of the three measures of one copy and two copies of the
antisymmetric projector states respectively. Third, we show, with a statistical
approach, that almost all multipartite pure states with sufficiently large
number of parties are nearly maximally entangled with respect to GM and
relative entropy of entanglement. However, their GM is not strong additive;
what's more surprising, for generic pure states with real entries in the
computational basis, GM of one copy and two copies, respectively, are almost
equal. Hence, more states may be suitable for universal quantum computation, if
measurements can be performed on two copies of the resource states. We also
show that almost all multipartite pure states cannot be produced reversibly
with the combination multipartite GHZ states under asymptotic LOCC, unless
relative entropy of entanglement is non-additive for generic multipartite pure
states.Comment: 45 pages, 4 figures. Proposition 23 and Theorem 24 are revised by
correcting a minor error from Eq. (A.2), (A.3) and (A.4) in the published
version. The abstract, introduction, and summary are also revised. All other
conclusions are unchange
Parabolic stable surfaces with constant mean curvature
We prove that if u is a bounded smooth function in the kernel of a
nonnegative Schrodinger operator on a parabolic Riemannian
manifold M, then u is either identically zero or it has no zeros on M, and the
linear space of such functions is 1-dimensional. We obtain consequences for
orientable, complete stable surfaces with constant mean curvature
in homogeneous spaces with four
dimensional isometry group. For instance, if M is an orientable, parabolic,
complete immersed surface with constant mean curvature H in
, then and if equality holds, then
M is either an entire graph or a vertical horocylinder.Comment: 15 pages, 1 figure. Minor changes have been incorporated (exchange
finite capacity by parabolicity, and simplify the proof of Theorem 1)
Completeness in hybrid type theory
We show that basic hybridization (adding nominals and @ operators) makes it possible to give straightforward Henkin-style completeness proofs even when the modal logic being hybridized is higher-order. The key ideas are to add nominals as expressions of type t, and to extend to arbitrary types the way we interpret @i in propositional and first-order hybrid logic. This means: interpret @iαa, where αa is an expression of any type a, as an expression of type a that rigidly returns the value that αa receives at the i-world. The axiomatization and completeness proofs are generalizations of those found in propositional and first-order hybrid logic, and (as is usual in hybrid logic) we automatically obtain a wide range of completeness results for stronger logics and languages. Our approach is deliberately low-tech. We don’t, for example, make use of Montague’s intensional type s, or Fitting-style intensional models; we build, as simply as we can, hybrid logic over Henkin’s logic.submittedVersionFil: Areces, Carlos Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Blackburn, Patrick. University of Roskilde. Centre for Culture and Identity. Department of Philosophy and Science Studies; Dinamarca.Fil: Huertas, Antonia. Universitat Oberta de Catalunya; España.Fil: Manzano, María. Universidad de Salamanca; España.Ciencias de la Computació
Ground-state correlation properties of charged bosons trapped in strongly anisotropic harmonic potentials
We study systems of a few charged bosons contained within a strongly
anisotropic harmonic trap. A detailed examination of the ground-state
correlation properties of two-, three-, and four-particle systems is carried
out within the framework of the single-mode approximation of the transverse
components. The linear correlation entropy of the quasi-1D systems is discussed
in dependence on the confinement anisotropy and compared with a strictly 1D
limit. Only at weak interaction the correlation properties depend strongly on
the anisotropy parameter.Comment: 5 pages, 6 figure
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