10,769 research outputs found
Entanglement detection in coupled particle plasmons
When in close contact, plasmonic resonances interact and become strongly
correlated. In this work we develop a quantum mechanical model, using the
language of continuous variables and quantum information, for an array of
coupled particle plasmons. This model predicts that when the coupling strength
between plasmons approaches or surpasses the local dissipation, a sizable
amount of entanglement is stored in the collective modes of the array. We also
prove that entanglement manifests itself in far-field images of the plasmonic
modes, through the statistics of the quadratures of the field, in what
constitutes a novel family of entanglement witnesses. This protocol is so
robust that it is indeed independent of whether our own model is correct.
Finally, we estimate the amount of entanglement, the coupling strength and the
correlation properties for a system that consists of two or more coupled
nanospheres of silver, showing evidence that our predictions could be tested
using present-day state-of-the-art technology.Comment: 8 pages (6 main text + 2 supplemental), 3 figure
Correlated hopping of bosonic atoms induced by optical lattices
In this work we analyze a particular setup with ultracold atoms trapped in
state-dependent lattices. We show that any asymmetry in the contact interaction
translates into one of two classes of correlated hopping. After deriving the
effective lattice Hamiltonian for the atoms, we obtain analytically and
numerically the different phases and quantum phase transitions. We find for
weak correlated hopping both Mott insulators and charge density waves, while
for stronger correlated hopping the system transitions into a pair superfluid.
We demonstrate that this phase exists for a wide range of interaction
asymmetries and has interesting correlation properties that differentiate it
from an ordinary atomic Bose-Einstein condensate.Comment: 24 pages with 9 figures, to appear in New Journal of Physic
On the resonances and polarizabilities of split ring resonators
In this paper, the behavior at resonance of split ring resonators SRRs and other related topologies,
such as the nonbianisotropic SRR and the broadside-coupled SRR, are studied. It is shown that these
structures exhibit a fundamental resonant mode the quasistatic resonance and other higher-order
modes which are related to dynamic processes. The excitation of these modes by means of a
properly polarized time varying magnetic and/or electric fields is discussed on the basis of resonator
symmetries. To verify the electromagnetic properties of these resonators, simulations based on
resonance excitation by nonuniform and uniform external fields have been performed. Inspection of
the currents at resonances, inferred from particle symmetries and full-wave electromagnetic
simulations, allows us to predict the first-order dipolar moments induced at the different resonators
and to develop a classification of the resonances based on this concept. The experimental data,
obtained in SRR-loaded waveguides, are in agreement with the theory and point out the rich
phenomenology associated with these planar resonant structures.MEC (España)-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comunidad Europea (programa Eureka)-2895 TELEMACAgencia de Subvenciones de la República Checa-102/03/044
Public sector wage gaps in Spanish regions.
This paper provides an approximation to the measurement of public sector wage gaps in Spanish regions. By using data from the European Community Household Panel, it is shown that the balance between what private firms pay in the local market and what the public sector pays, differs substantially in different areas of the country. Public sector wage differences among Spanish regions are mostly due to differences in returns, not to differences in characteristics or to selection effects, and are not constant across gender, educational levels, or occupations. Moreover, in those regions where Regional Governments have a higher weight in public employment, public wage gaps are higher and public employers pay higher returns. There also seems to be a cross-regional positive correlation between public wage gaps and unemployment, and a negative one between labour productivity and public wage gaps. Hence, a tentative conclusion is that the incentives to select into the public sector are higher in the low productivity regions, precisely those where scarcity of human capital in the private sector may be the most important factor for explaining economic backwardness.public sector, wage differentials, switching regressions, Spanish regions.
Acoustical Behavior Of Churches: Mudejar-Gothic Churches
Christian churches have traditionally been considered to have very good acoustical behavior. This unfounded belief has led to
important en-on in church rehabilitation works, especially when the church is to be used subsequently as an auditorium or theater; this
is the case of many churches in Spain. Our research group has worked in acoustical analysis for more than ten years. We have
participated in many cases of church rehabilitation and have had the opp&unity to achieve surprisingly good acwstical behavior in
several. We deal with a very common type in southern Spain: Gothic-Mudejar churches, which have a small volume, a triple-nave
layout, and wooden ceilings
Quantum Ratchets for Quantum Communication with Optical Superlattices
We propose to use a quantum ratchet to transport quantum information in a
chain of atoms trapped in an optical superlattice. The quantum ratchet is
created by a continuous modulation of the optical superlattice which is
periodic in time and in space. Though there is zero average force acting on the
atoms, we show that indeed the ratchet effect permits atoms on even and odd
sites to move along opposite directions. By loading the optical lattice with
two-level bosonic atoms, this scheme permits to perfectly transport a qubit or
entangled state imprinted in one or more atoms to any desired position in the
lattice. From the quantum computation point of view, the transport is achieved
by a smooth concatenation of perfect swap gates. We analyze setups with
noninteracting and interacting particles and in the latter case we use the
tools of optimal control to design optimal modulations. We also discuss the
feasibility of this method in current experiments.Comment: Published version, 9 pages, 5 figure
RESEARCH IN ECONOMICS IN SPAIN: RANKINGS OF INSTITUTIONS AND AUTHORS
In this paper we analyse the research in Economics in Spain during the 1990s considering the contributions of both Spanish and foreign economist who have worked in Spain during that period. To do so, we use different bibliometric indicators in order to elaborate rankings for both institutions and researchers. These rankings can be useful for several potentials users such as: a) Evaluation Agencies and Funding Bodies to help them in grant-allocation decisions; b) Graduate students who whish to choose the right institution to complete their postgraduate education, and c) Young Ph Ds who have entered the academic job market and need information about the research perfomance of different institutions.
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