4,353 research outputs found
Quantum Simulation of Interacting Fermion Lattice Models in Trapped Ions
We propose a method of simulating efficiently many-body interacting fermion
lattice models in trapped ions, including highly nonlinear interactions in
arbitrary spatial dimensions and for arbitrarily distant couplings. We map
products of fermionic operators onto nonlocal spin operators and decompose the
resulting dynamics in efficient steps with Trotter methods, yielding an overall
protocol that employs only polynomial resources. The proposed scheme can be
relevant in a variety of fields as condensed-matter or high-energy physics,
where quantum simulations may solve problems intractable for classical
computers.Comment: 5 pages, 2 figures + Supplementary Materia
Can the Visits of Dogs (Canis lupus familiaris) Influence the Mental Health (Anxiety and Depression) of Male Aging Patients Institutionalized with Dementia in Health Care Units? A Pilot Study of Madeira Island, Portugal
Despite the fact that in the last decades, several mental health studies have shown
that companion animals contribute to psychological and social well-being in humans (e.g., posi tive impacts have been observed in the elderly medicated for chronic diseases such as anxiety,
dementia, and depression), bonds between humans and other animals continue to be under estimated. The aim of this study is to assess the impact of an animal’s visits (twice a week, N =
30) in depression and anxiety levels of an institutionalized male population diagnosed with de mentia. While some of these patients are being partially medicated with antidepressants and/or
anxiolytics, others are not subject to any medication (control group). The GAI and GDS measur ing instruments were used and there were differences in anxiety and depression levels between
the first and last dog visit, statistically significant in depression levels of nonmedicated patients.
Such findings allow us to conclude that the effects of the visits of an animal near nonmedicated
patients are greater than near medicated ones. The complementary role of animals in mental
health institutions where patients are being treated for psychiatric disorders (in the particular
case of dementia) should be considered.info:eu-repo/semantics/publishedVersio
Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions
The thermoelectric properties of intermetallic compounds with Ce or Yb ions
are explained by the single-impurity Anderson model which takes into account
the crystal-field splitting of the 4{\it f} ground-state multiplet, and assumes
a strong Coulomb repulsion which restricts the number of {\it f} electrons or
{\it f} holes to for Ce and for Yb ions. Using
the non-crossing approximation and imposing the charge neutrality constraint on
the local scattering problem at each temperature and pressure, the excitation
spectrum and the transport coefficients of the model are obtained. The
thermopower calculated in such a way exhibits all the characteristic features
observed in Ce and Yb intermetallics. Calculating the effect of pressure on
various characteristic energy scales of the model, we obtain the phase
diagram which agrees with the experimental data on CeRuSi,
CeCuSi, CePdSi, and similar compounds. The evolution of the
thermopower and the electrical resistance as a function of temperature,
pressure or doping is explained in terms of the crossovers between various
fixed points of the model and the redistribution of the single-particle
spectral weight within the Fermi window.Comment: 13 pages, 11 figure
The AMIGA sample of isolated galaxies - II. Morphological refinement
We present a complete POSS II-based refinement of the optical morphologies
for galaxies in the Karatchenseva's Catalog of Isolated Galaxies that forms the
basis of the AMIGA project. Comparison with independent classifications made
for an SDSS overlap sample of more than 200 galaxies confirms the reliability
of the early vs. late-type discrimination and the accuracy of spiral subtypes
within DeltaT = 1-2. CCD images taken at the OSN were also used to solve
ambiguities. 193 galaxies are flagged for the presence of nearby companions or
signs of distortion likely due to interaction. This most isolated sample of
galaxies in the local Universe is dominated by 2 populations: 1) 82% spirals
(Sa-Sd) with the bulk being luminous systems with small bulges (63% between
types Sb-Sc) and 2) a significant population of early-type E-S0 galaxies (14%).
Most of the types later than Sd are low luminosity galaxies concentrated in the
local supercluster where isolation is difficult to evaluate. The late-type
spiral majority of the sample spans a luminosity range M_B-corr = -18 to -22
mag. Few of the E/S0 population are more luminous than -21.0 marking an absence
of, an often sought, super L* merger (eg fossil elliptical) population. The
rarity of high luminosity systems results in a fainter derived M* for this
population compared to the spiral optical luminosity function (OLF). The E-S0
population is from 0.2 to 0.6 mag fainter depending how the sample is defined.
This marks the AMIGA sample as almost unique among samples that compare early
and late-type OLFs separately. In other samples, which always involve galaxies
in higher density environments, M*(E/S0) is almost always 0.3-0.5 mag brighter
than M*(S), presumably reflecting a stronger correlation between M* and
environmental density for early-type galaxies.Comment: A&A accepted, 13 pages, 9 figures, 8 tables. Higher resolution Fig. 1
and full tables are available on the AMIGA (Analysis of the interstellar
Medium of Isolated GAlaxies) website at http://www.iaa.es/AMIGA.htm
Quantum Simulation of Spin Chains Coupled to Bosonic Modes with Superconducting Circuits
We propose the implementation of a digital quantum simulation of spin chains
coupled to bosonic field modes in superconducting circuits. Gates with high
fidelities allows one to simulate a variety of Ising magnetic pairing
interactions with transverse field, Tavis-Cummings interaction between spins
and a bosonic mode, and a spin model with three-body terms. We analyze the
feasibility of the implementation in realistic circuit quantum electrodynamics
setups, where the interactions are either realized via capacitive couplings or
mediated by microwave resonators.Comment: Chapter in R. S. Anderssen et al. (eds.), Mathematics for Industry 11
(Springer Japan, 2015
The nonrelativistic limit of the Majorana equation and its simulation in trapped ions
We analyze the Majorana equation in the limit where the particle is at rest.
We show that several counterintuitive features, absent in the rest limit of the
Dirac equation, do appear. Among them, Dirac-like positive energy solutions
that turn into negative energy ones by free evolution, or nonstandard
oscillations and interference between real and imaginary spinor components for
complex solutions. We also study the ultrarelativistic limit, showing that the
Majorana and Dirac equations mutually converge. Furthermore, we propose a
physical implementation in trapped ions.Comment: 7 pages, 1 figure. Proceedings of 18th Central European Workshop on
Quantum Optics (CEWQO 2011), Madrid, Spai
Relativistic quantum mechanics with trapped ions
We consider the quantum simulation of relativistic quantum mechanics, as
described by the Dirac equation and classical potentials, in trapped-ion
systems. We concentrate on three problems of growing complexity. First, we
study the bidimensional relativistic scattering of single Dirac particles by a
linear potential. Furthermore, we explore the case of a Dirac particle in a
magnetic field and its topological properties. Finally, we analyze the problem
of two Dirac particles that are coupled by a controllable and confining
potential. The latter interaction may be useful to study important phenomena as
the confinement and asymptotic freedom of quarks.Comment: 17 pages, 4 figure
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