2,189 research outputs found
Electro-spinon in one-dimensional Mott insulator
The low-energy dynamical optical response of dimerized and undimerized spin
liquid states in a one-dimensional charge transfer Mott insulator is
theoretically studied. An exact analysis is given for the low-energy asymptotic
behavior using conformal field theory for the undimerized state. In the
dimerized state, the infrared absorption due to the bound state of two
solitons, i.e, the breather mode, is predicted with an accurate estimate for
its oscillator strength, offering a way to detect experimentally the excited
singlet state. Effects of external magnetic fields are also discussed.Comment: 5 pages, 2 figures, some typos are correcte
Incoherent Noise and Quantum Information Processing
Incoherence in the controlled Hamiltonian is an important limitation on the
precision of coherent control in quantum information processing. Incoherence
can typically be modelled as a distribution of unitary processes arising from
slowly varying experimental parameters. We show how it introduces artifacts in
quantum process tomography and we explain how the resulting estimate of the
superoperator may not be completely positive. We then go on to attack the
inverse problem of extracting an effective distribution of unitaries that
characterizes the incoherence via a perturbation theory analysis of the
superoperator eigenvalue spectra.Comment: 15 pages, 5 figures, replaced with future JCP published versio
Eosinophils, probiotics, and the microbiome
There is currently substantial interest in the therapeutic
properties of probiotic microorganisms as recent research suggests that oral administration of specific
bacterial strains may reduce inflammation and alter the
nature of endogenous microflora in the gastrointestinal
tract. Eosinophils are multifunctional tissue leukocytes,
prominent among the resident cells of the gastrointestinal mucosa that promote local immunity. Recent studies
with genetically altered mice indicate that eosinophils not
only participate in maintaining gut homeostasis, but that
the absence of eosinophils may have significant impact
on the nature of the endogenous gut microflora and
responses to gut pathogens, notably Clostridium difficile.
Furthermore, in human subjects, there is an intriguing
relationship between eosinophils, allergic inflammation,
and the nature of the lung microflora, notably a distinct
association between eosinophil infiltration and detection
of bacteria of the phylum Actinobacteria. Among topics
for future research, it will be important to determine
whether homeostatic mechanisms involve direct interactions between eosinophils and bacteria or whether
they involve primarily eosinophil-mediated responses to
cytokine signaling in the local microenvironment. Likewise, although is it clear that eosinophils can and do
interact with bacteria in vivo, their ability to discern
between pathogenic and probiotic species in various
settings remains to be explored
Energetic perspective on emergent inductance exhibited by magnetic textures in the pinned regime
Spatially varying magnetic textures can exhibit electric-current-induced
dynamics as a result of the spin-transfer torque effect. When such a magnetic
system is electrically driven, an electric field is generated, which is called
the emergent electric field. In particular, when magnetic-texture dynamics are
induced under the application of an AC electric current, the emergent electric
field also appears in an AC manner, notably, with an out-of-phase time profile,
thus exhibiting inductor behaviour, often called an emergent inductor. Here we
show that the emergent inductance exhibited by magnetic textures in the pinned
regime can be explained in terms of the current-induced energy stored in the
magnetic system. We numerically find that the inductance values defined from
the emergent electric field and the current-induced magnetization-distortion
energy, respectively, are in quantitative agreement in the so-called adiabatic
limit. Our findings indicate that emergent inductors retain the basic concept
of conventional inductors; that is, the energy is stored under the application
of electric current
Field Emission Dark Current of Technical Metallic Electrodes
In the framework of the Low Emittance Gun (LEG) project, high gradient
acceleration of a low emittance electron beam will be necessary. In order to
achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in
between two electrodes. Those electrodes should sustain the pulsed field
without arcing, must not outgass and must not emit electrons. Ion back
bombardment, and dark current will be damageable to the electron source as well
as for the low emittance beam. Electrodes of commercially available OFE copper,
aluminium, stainless steel, titanium and molybdenum were tested following
different procedures including plasma glow discharge cleaning.Comment: 22 pages, 6 tables, 10 figures Vs 2 : graphics more readable,
enhanced content Vs 3 : typo correcte
Fundamental properties of Tsallis relative entropy
Fundamental properties for the Tsallis relative entropy in both classical and
quantum systems are studied. As one of our main results, we give the parametric
extension of the trace inequality between the quantum relative entropy and the
minus of the trace of the relative operator entropy given by Hiai and Petz. The
monotonicity of the quantum Tsallis relative entropy for the trace preserving
completely positive linear map is also shown without the assumption that the
density operators are invertible.
The generalized Tsallis relative entropy is defined and its subadditivity is
shown by its joint convexity. Moreover, the generalized Peierls-Bogoliubov
inequality is also proven
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