5,361 research outputs found
Collective and Single-particle Motion in Beyond Mean Field Approaches
We present a novel nuclear energy density functional method to calculate
spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole
deformations and rotational frequencies are considered simultaneously as the
degrees of freedom within a symmetry conserving configuration mixing framework.
The present method allows the study of nuclear states with collective and
single-particle character. We calculate the fascinating structure of the
semi-magic 44S nucleus as a first application of the method, obtaining an
excellent quantitative agreement both with the available experimental data and
with state-of-the-art shell model calculations.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let
Quantum Spin Dimers from Chiral Dissipation in Cold-Atom Chains
We consider the non-equilibrium dynamics of a driven dissipative spin chain
with chiral coupling to a 1D bosonic bath, and its atomic implementation with a
two-species mixture of cold quantum gases. The reservoir is represented by a
spin-orbit coupled 1D quasi-condensate of atoms in a magnetized phase, while
the spins are identified with motional states of a separate species of atoms in
an optical lattice. The chirality of reservoir excitations allows the spins to
couple differently to left and right moving modes, which in our atomic setup
can be tuned from bidirectional to purely unidirectional. Remarkably, this
leads to a pure steady state in which pairs of neighboring spins form dimers
that decouple from the remainder of the chain. Our results also apply to
current experiments with two-level emitters coupled to photonic waveguides.Comment: Replaced by published version (6 pages + 8 pages supplemental
material
Large amplitude pairing fluctuations in atomic nuclei
Pairing fluctuations are self-consistently incorporated on the same footing
as the quadrupole deformations in present state of the art calculations
including particle number and angular momentum conservation as well as
configuration mixing. The approach is complemented by the use of the finite
range density dependent Gogny force which, with a unique source for the
particle-hole and particle-particle interactions, guarantees a self-consistent
interplay in both channels.
We have applied our formalism to study the role of the pairing degree of
freedom in the description of the most relevant observables like spectra,
transition probabilities, separation energies, etc. We find that the inclusion
of pairing fluctuations mostly affects the description of excited states,
depending on the excitation energy and the angular momentum. transition
probabilities experiment rather big changes while 's are less affected.
Genuine pairing vibrations are thoroughly studied with the conclusion that
deformations strongly inhibits their existence. These studies have been
performed for a selection of nuclei: spherical, deformed and with different
degree of collectivity.Comment: 23 pages, 23 Figures, To be published in Phys. Rev.
Nonlinear Quantum Optomechanics via Individual Intrinsic Two-Level Defects
We propose to use the intrinsic two-level system (TLS) defect states found
naturally in integrated optomechanical devices for exploring cavity QED-like
phenomena with localized phonons. The Jaynes-Cummings-type interaction between
TLS and mechanics can reach the strong coupling regime for existing
nano-optomechanical systems, observable via clear signatures in the
optomechanical output spectrum. These signatures persist even at finite
temperature, and we derive an explicit expression for the temperature at which
they vanish. Further, the ability to drive the defect with a microwave field
allows for realization of phonon blockade, and the available controls are
sufficient to deterministically prepare non-classical states of the mechanical
resonator.Comment: Comments welcome (5+7 pages), Final Published Versio
Triaxial Angular Momentum Projection and Configuration Mixing calculations with the Gogny force
We present the first implementation in the plane of the
generator coordinate method with full triaxial angular momentum and particle
number projected wave functions using the Gogny force. Technical details about
the performance of the method and the convergence of the results both in the
symmetry restoration and the configuration mixing parts are discussed in
detail. We apply the method to the study of Mg, the calculated energies
of excited states as well as the transition probabilities are compared to the
available experimental data showing a good overall agreement. In addition, we
present the RVAMPIR approach which provides a good description of the ground
and gamma bands in the absence of strong mixing.Comment: 40 pages,14 figure
Mosaic multi-state scenario vs. one-state description of supercooled liquids
According to the mosaic scenario, relaxation in supercooled liquids is ruled
by two competing mechanisms: surface tension, opposing the creation of local
excitations, and entropy, providing the drive to the configurational
rearrangement of a given region. We test this scenario through numerical
simulations well below the Mode Coupling temperature. For an equilibrated
configuration, we freeze all the particles outside a sphere and study the
thermodynamics of this sphere. The frozen environment acts as a pinning field.
Measuring the overlap between the unpinned and pinned equilibrium
configurations of the sphere, we can see whether it has switched to a different
state. We do not find any clear evidence of the mosaic scenario. Rather, our
results seem compatible with the existence of a single (liquid) state. However,
we find evidence of a growing static correlation length, apparently unrelated
to the mosaic one.Comment: 4 pages, 3 figures, final version accepted in PR
Variational Methods in AdS/CFT
We prove that the AdS/CFT calculation of 1-point functions can be drastically
simplified by using variational arguments. We give a simple universal proof,
valid for any theory that can be derived from a Lagrangian, that the large
radius divergencies in 1-point functions can always be renormalized away (at
least in the semiclassical approximation). The renormalized 1-point functions
then follow by a simple variational problem involving only finite quantities.
Several examples, a massive scalar, gravity, and renormalization flows, are
discussed. Our results are general and can thus be used for dualities beyond
AdS/CFT.Comment: 14 pages, no figures, LaTeX, minor change in footnot
Influencia de las aleaciones metálicas en el color de la cerámica
El efecto cromático final de las restauraciones metalo-cerámicas se ve influenciado por el tipo de aleación metálica usada en su realización. En este estudio hemos realizado un análisis calorimétrico de 50 especÃmenes donde se combinan dos colores y cinco aleaciones diferentes. Después del análisis estadÃstico pertinente, se ha concluido que las aleaciones de base paladio plata son las que producen una variación más notoria del color, aumentando la saturación de amarillo y verde
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