234 research outputs found
Constraint on Neutrino Decay with Medium-Baseline Reactor Neutrino Oscillation Experiments
The experimental bound on lifetime of nu_3, the neutrino mass eigenstate with
the smallest nu_e component, is much weaker than those of nu_1 and nu_2 by many
orders of magnitude to which the astrophysical constraints apply. We argue that
the future reactor neutrino oscillation experiments with medium-baseline (~ 50
km), such as JUNO or RENO-50, has the best chance of placing the most stringent
constraint on nu_3 lifetime among all neutrino experiments which utilize the
artificial source neutrinos. Assuming decay into invisible states, we show by a
detailed chi^2 analysis that the nu_3 lifetime divided by its mass, tau_3/m_3,
can be constrained to be tau_3/m_3 > 7.5 (5.5) x 10^{-11} s/eV at 95% (99%)
C.L. by 100 kt.years exposure by JUNO. It may be further improved to the level
comparable to the atmospheric neutrino bound by its longer run. We also discuss
to what extent nu_3 decay affects mass-ordering determination and precision
measurements of the mixing parameters.Comment: 23 pages, 6 figures, clarification of some discussions, added some
references, no change in results and conclusions, version accepted for
publication in JHE
Boson Sampling with efficient scaling and efficient verification
A universal quantum computer of moderate scale is not available yet, however
intermediate models of quantum computation would still permit demonstrations of
a quantum computational advantage over classical computing and could challenge
the Extended Church-Turing Thesis. One of these models based on single photons
interacting via linear optics is called Boson Sampling. Proof-of-principle
Boson Sampling has been demonstrated, but the number of photons used for these
demonstrations is below the level required to claim quantum computational
advantage. To make progress with this problem, here we conclude that the most
practically achievable pathway to scale Boson Sampling experiments with current
technologies is by combining continuous-variables quantum information and
temporal encoding. We propose the use of switchable dual-homodyne and
single-photon detections, the temporal loop technique and scattershot based
Boson Sampling. This proposal gives details as to what the required assumptions
are and a pathway for a quantum optical demonstration of quantum computational
advantage. Furthermore, this particular combination of techniques permits a
single efficient implementation of Boson Sampling and efficient verification in
a single experimental setup
Resources Package Modelling Supporting Border Surveillance Operations
The purpose of this work is to propose a military planning tool capable of providing logistical bases and patrol packages to most effectively support border surveillance. Presently, military patrols are employed along geographical borders to combat transnational crimes; acts such as drug trafficking, smuggling of goods and illegal natural resources exploitation. The patrols make temporary stops within specific time windows at specific places characterised by a high incidence of crime (hotspots). These hotspots have different criticalities within given time windows. To optimise the results, the proposed model allows additional stops in more critical hotspots. It achieves this using a mathematical optimisation model. Considering that there are not adequate logistical-military capacities (logistical bases and patrols) at all needed locations, developing a border surveillance plan that optimises resource use is imperative. The model was run using black hole-based optimisation and a real patrol mission’s database to ensure timely solutions. The solutions were then evaluated in terms of quality (number of bases and patrols, coverage efforts, and travel time) and computational processing time. Next, they were compared with solutions using the traditional method, thereby demonstrating the model’s robustness in providing timely surveillance schemes that ensure high coverage with minimum resources
Quantum metrology timing limits of the Hong-Ou-Mandel interferometer and of general two-photon measurements
We examine the precision limits of Hong-Ou-Mandel (HOM) timing measurements,
as well as precision limits applying to generalized two-photon measurements. As
a special case, we consider the use of two-photon measurements using photons
with variable bandwidths and frequency correlations. When the photon bandwidths
are not equal, maximizing the measurement precision involves a trade-off
between high interference visibility and strong frequency anticorrelations,
with the optimal precision occuring when the photons share non-maximal
frequency anticorrelations. We show that a generalized measurement has
precision limits that are qualitatively similar to those of the HOM measurement
whenever the generalized measurement is insensitive to the net delay of both
photons. By examining the performance of states with more general frequency
distributions, our analysis allows for engineering of the joint spectral
amplitude for use in realistic situations, in which both photons may not have
ideal spectral properties.Comment: 12 pages, 6 figures; resubmissio
Spectral characterization of a SPDC source with a fast broadband spectrometer
Knowing the properties of the single photons produced in a Spontaneous
Parametric Down-Conversion (SPDC) source can be crucial for specific
applications and uses. In particular, the spectral properties are of key
relevance. Here, we investigate a commercial SPDC source using our fast
broadband spectrometer. Our analysis is a valid method for other SPDC sources,
as well as other single-photon generation techniques, thus providing a good
example of how to use this spectrometer design. We calibrate the spectrometer
using known lines of the argon emission spectrum. We show that the two
down-converted photons from the SPDC source have different spectral properties
depending on the pump power, and in which condition we measured spectrally
similar down-converted photons. Lastly, we were able to reconstruct and
investigate the spectral information for the pump photon
Towards Quantum Telescopes: Demonstration of a Two-Photon Interferometer for Quantum-Assisted Astronomy
Classical optical interferometery requires maintaining live, phase-stable
links between telescope stations. This requirement greatly adds to the cost of
extending to long baseline separations, and limits on baselines will in turn
limit the achievable angular resolution. Here we describe a novel type of
two-photon interferometer for astrometry, which uses photons from two separate
sky sources and does not require an optical link between stations. Such
techniques may make large increases in interferometric baselines practical,
even by orders of magnitude, with corresponding improvement in astrometric
precision benefiting numerous fields in astrophysics. We tested a benchtop
analogue version of the two-source interferometer and unambiguously observe
correlated behavior in detections of photon pairs from two thermal light
sources, in agreement with theoretical predictions. This work opens new
possibilities in future astronomical measurements
Fast spectrometer near the Heisenberg limit with direct measurement of time and frequency for multiple single photons
We present a single-photon-sensitive spectrometer, based on a linear array of
512 single-photon avalanche diodes, with 0.04 nm spectral and 40 ps temporal
resolutions. We employ a fast data-driven operation that allows direct
measurement of time and frequency for simultaneous single photons. Combining
excellent temporal and spectral resolution, our result is only a factor of ten
above the Heisenberg Uncertainty Principle limit of hbar/2 for energy and time,
despite the simplicity of our experimental setup. This work opens numerous
applications in quantum photonics, especially when both spectral and temporal
properties of single photons are exploited
Avaliação da qualidade vocal de crianças sem queixas vocais: estudo prospectivo duplo-cego
OBJECTIVE: To evaluate the vocal quality of children without voice disorders, analyzing the possible presence and type of lesion, glottic coaptation and laryngeal constriction, roughness and breathiness vocal quality.MATERIALS AND METHODS: We evaluated 50 male children, aged 3 to 10, randomly selected, who did not present otorhinolaryngological disorders. All children went through an otorhinolaryngological exam, followed by videofibrolaryngoscopy and speech pathology evaluation.RESULTS: Out of the 50 children, 25 were classified as normal. Eight presented with cysts, and 17 had vocal nodules. We observed that normal vocal quality was significant in the normal group, while roughness and breathness were associated with the pathological group. We did not find a significant difference in vocal quality when we analyzed glottic coaptation and laryngeal constriction.CONCLUSIONS: Roughness and breathness were significantly associated with structural lesions of the vocal fold, while a normal vocal quality was associated with absence of structural lesions. The authors concluded that all signs of roughness or breathness should be considered in order to allow an early diagnosis of laryngeal alterations and, consequently, early treatment.OBJETIVO: Avaliar a qualidade vocal de crianças que não apresentam queixas de distúrbios na voz. As crianças foram analisadas quanto à possÃvel presença e tipo delesão, quanto ao tipo de coaptação das pregas vocais, e quanto à rouquidão, aspereza e soprosidade da voz.MATERIAIS E MÉTODOS: Foram avalidas 50 crianças do sexo masculino, escolhidas aleatoriamente, na faixa etária de 3 a 10 anos, que não apresentavam queixasotorrinolaringológicas. To das as crianças passaram por exame otorrinolaringológico, seguido de videofibrolaringoscopia e avaliação fonoaudiolóigica.RESULTADOS: Das 50 crianças, 25 foram classificadas como normais. Oito eram portadoras de cisto e 17, portadoras de nódulo vocal, todas sem queixas vocais.Observamos que a qualidade vocal normal esteve presente de maneira significativa no grupo normal, enquanto a rouquidão e a soprosidade estiveram associadas de maneira significativa ao grupo patológico. Nós não observamos diferença significativaquanto a qualidade vocal ao analisarmos a coaptação glótica e a constrição larÃngea.CONCLUSÕES: A qualidade vocal do tipo rouca e soprosa está associada de maneira significativa à s com lesão estrutural das pregas vocais e a qualidade vocal normal, à s crianças sem lesão estrutural. Assim, deve-se atentar para a presença de rouquidão em crianças de forma a permitir o diagnóstico precoce de alterações larÃngeas e, conseqüentemente, a terapêutica
Contraction amplitude is a relevant predictor of bolus transit during sitting viscous solution swallows in healthy individuals : preliminary results of a multicenter study using high resolution impedance manometry (HRIM)
Q1Q1https://orcid.org/0000-0002-9219-4548https://orcid.org/0000-0003-1222-0636https://orcid.org/0000-0002-4523-7947Revista Internacional - Indexad
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