450 research outputs found
Generation of one-million-mode continuous-variable cluster state by unlimited time-domain multiplexing
In recent quantum optical continuous-variable experiments, the number of
fully inseparable light modes has drastically increased by introducing a
multiplexing scheme either in the time domain or in the frequency domain. Here,
modifying the time-domain multiplexing experiment reported in Nature Photonics
7, 982 (2013), we demonstrate successive generation of fully inseparable light
modes for more than one million modes. The resulting multi-mode state is useful
as a dual-rail CV cluster state. We circumvent the previous problem of optical
phase drifts, which has limited the number of fully inseparable light modes to
around ten thousands, by continuous feedback control of the optical system.Comment: 12 pages, 8 figure
Nanoelectromechanical coupling in fullerene peapods probed via resonant electrical transport experiments
Fullerene peapods, that is carbon nanotubes encapsulating fullerene
molecules, can offer enhanced functionality with respect to empty nanotubes.
However, the present incomplete understanding of how a nanotube is affected by
entrapped fullerenes is an obstacle for peapods to reach their full potential
in nanoscale electronic applications. Here, we investigate the effect of C60
fullerenes on electron transport via peapod quantum dots. Compared to empty
nanotubes, we find an abnormal temperature dependence of Coulomb blockade
oscillations, indicating the presence of a nanoelectromechanical coupling
between electronic states of the nanotube and mechanical vibrations of the
fullerenes. This provides a method to detect the C60 presence and to probe the
interplay between electrical and mechanical excitations in peapods, which thus
emerge as a new class of nanoelectromechanical systems.Comment: 7 pages, 3 figures. Published in Nature Communications. Free online
access to the published version until Sept 30th, 2010, see
http://www.nature.com/ncomms/journal/v1/n4/abs/ncomms1034.htm
Probing the neutrino mass hierarchy and the 13-mixing with supernovae
We consider in details the effects of the 13-mixing (sin^2 theta_{13}) and of
the type of mass hierarchy/ordering (sign[ Delta m^2_{13}]) on neutrino signals
from the gravitational collapses of stars. The observables (characteristics of
the energy spectra of nu_e and antinu_e events) sensitive to sin^2 theta_{13}
and sign[Delta m^2_{13}] have been calculated. They include the ratio of
average energies of the spectra, r_E = /, the ratio of widths of
the energy distributions, r_Gamma, the ratios of total numbers of nu_e and
antinu_e events at low energies, S, and in the high energy tails, R_{tail}. We
construct and analyze scatter plots which show the predictions for the
observables for different intervals of sin^2 theta_{13} and signs of Delta
m^2_{13}, taking into account uncertainties in the original neutrino spectra,
the star density profile, etc.. Regions in the space of observables r_E,
r_Gamma, S, R_{tail} exist in which certain mass hierarchy and intervals of
sin^2 theta_{13} can be identified or discriminated. We elaborate on the method
of the high energy tails in the spectra of events. The conditions are
formulated for which sin^2 theta_{13} can be (i) measured, (ii) restricted from
below, (iii) restricted from above. We comment on the possibility to determine
sin^2 theta_{13} using the time dependence of the signals due to the
propagation of the shock wave through the resonance layers of the star. We show
that the appearance of the delayed Earth matter effect in one of the channels
(nu_e or antinu_e) in combination with the undelayed effect in the other
channel will allow to identify the shock wave appeareance and determine the
mass hierarchy.Comment: LaTeX, 56 pages, 12 figures; a few clarifications added; typos
corrected. Version to appear in JCA
Advances in Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma
Stereotactic Body Radiation Therapy (SBRT) is an emerging effective treatment for hepatocellular carcinoma (HCC) associated with acceptable rates of toxicity in appropriately selected patients. Despite often being reserved for patients unsuitable for other local treatments, prospective and retrospective studies have demonstrated excellent long-term control. SBRT may be used as a stand-alone treatment, or as an adjunct to other HCC therapies. Based on available data, SBRT appears to complement existing local liver therapies. Randomized and nonrandomized comparative studies are required to better determine the optimal role of SBRT in HCC treatment
Supernova neutrinos: difference of nu_mu - nu_tau fluxes and conversion effects
The formalism of flavor conversion of supernova neutrinos is generalized to
include possible differences in the fluxes of the muon and tau neutrinos
produced in the star. In this case the radiatively induced difference of the
nu_mu and nu_tau potentials in matter becomes important. The nu_mu and nu_tau
flux differences can manifest themselves in the effects of the Earth matter on
the observed nu_e (antinu_e) signal if: (i) the neutrino mass hierarchy is
normal (inverted); (ii) the solution of the solar neutrino problem is in the
LMA region; (iii) the mixing U_{e3} is relatively large: |U_{e3}|>10^{-3}. We
find that for differences in the nu_mu - nu_tau (antinu_mu - antinu_tau)
average energies and/or integrated luminosities < 20 %, the relative deviation
of the observed nu_e (antinu_e) energy spectrum at E > 50 MeV from that in the
case of the equal fluxes can reach 20 - 30 % (10 - 15 %) for neutrinos crossing
the Earth. It could be detected in future if large detectors sensitive to the
nu_e (antinu_e) energy spectrum become available. The study of this effect
would allow one to test the predictions of the nu_mu, nu_tau, antinu_mu,
antinu_tau fluxes from supernova models and therefore give an important insight
into the properties of matter at extreme conditions. It should be taken into
account in the reconstruction of the neutrino mass spectrum and mixing matrix
from the supernova neutrino observations. We show that even for unequal nu_mu
and nu_tau fluxes, effects of leptonic CP violation can not be studied in the
supernova neutrino experiments.Comment: LaTeX, 34 pages, 10 figures; minor changes to text and figures,
references and acknowledgements adde
Experimental study of the atmospheric neutrino backgrounds for proton decay to positron and neutral pion searches in water Cherenkov detectors
The atmospheric neutrino background for proton decay to positron and neutral
pion in ring imaging water Cherenkov detectors is studied with an artificial
accelerator neutrino beam for the first time. In total, about 314,000 neutrino
events corresponding to about 10 megaton-years of atmospheric neutrino
interactions were collected by a 1,000 ton water Cherenkov detector (KT). The
KT charged-current single neutral pion production data are well reproduced by
simulation programs of neutrino and secondary hadronic interactions used in the
Super-Kamiokande (SK) proton decay search. The obtained proton to positron and
neutral pion background rate by the KT data for SK from the atmospheric
neutrinos whose energies are below 3 GeV is about two per megaton-year. This
result is also relevant to possible future, megaton-scale water Cherenkov
detectors.Comment: 13 pages, 16 figure
Search for coherent charged pion production in neutrino-carbon interactions
We report the result from a search for charged-current coherent pion
production induced by muon neutrinos with a mean energy of 1.3 GeV. The data
are collected with a fully active scintillator detector in the K2K
long-baseline neutrino oscillation experiment. No evidence for coherent pion
production is observed and an upper limit of is set on
the cross section ratio of coherent pion production to the total
charged-current interaction at 90% confidence level. This is the first
experimental limit for coherent charged pion production in the energy region of
a few GeV.Comment: 5 pages, 4 figure
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