23,625 research outputs found
Zero-field and Larmor spinor precessions in a neutron polarimeter experiment
We present a neutron polarimetric experiment where two kinds of spinor
precessions are observed: one is induced by different total energy of neutrons
(zero-field precession) and the other is induced by a stationary guide field
(Larmor precession). A characteristic of the former is the dependence of the
energy-difference, which is in practice tuned by the frequency of the
interacting oscillating magnetic field. In contrast the latter completely
depends on the strength of the guide field, namely Larmor frequency. Our
neutron-polarimetric experiment exhibits individual tuning as well as specific
properties of each spinor precession, which assures the use of both spin
precessions for multi-entangled spinor manipulation.Comment: 12 pages, 4 figure
Mechanism of Ambipolar Field-Effect Carrier Injections in One-Dimensional Mott Insulators
To clarify the mechanism of recently reported, ambipolar carrier injections
into quasi-one-dimensional Mott insulators on which field-effect transistors
are fabricated, we employ the one-dimensional Hubbard model attached to a
tight-binding model for source and drain electrodes. To take account of the
formation of Schottky barriers, we add scalar and vector potentials, which
satisfy the Poisson equation with boundary values depending on the drain
voltage, the gate bias, and the work-function difference. The current-voltage
characteristics are obtained by solving the time-dependent Schr\"odinger
equation in the unrestricted Hartree-Fock approximation. Its validity is
discussed with the help of the Lanczos method applied to small systems. We find
generally ambipolar carrier injections in Mott insulators even if the work
function of the crystal is quite different from that of the electrodes. They
result from balancing the correlation effect with the barrier effect. For the
gate-bias polarity with higher Schottky barriers, the correlation effect is
weakened accordingly, owing to collective transport in the one-dimensional
correlated electron systems.Comment: 21 pages, 10 figures, to appear in J. Phys. Soc. Jp
Recombination kinetics of a dense electron-hole plasma in strontium titanate
We investigated the nanosecond-scale time decay of the blue-green light
emitted by nominally pure SrTiO following the absorption of an intense
picosecond laser pulse generating a high density of electron-hole pairs. Two
independent components are identified in the fluorescence signal that show a
different dynamics with varying excitation intensity, and which can be
respectively modeled as a bimolecular and unimolecolar process. An
interpretation of the observed recombination kinetics in terms of interacting
electron and hole polarons is proposed
Kinematics of Red Variables in the Solar Neighborhood I. Basic Data Obtained by an SiO Maser Survey
In order to study the streaming motions of miras in the Solar neighborhood,
we newly surveyed 379 red variables in the SiO maser lines at 42.821 and 43.122
GHz with the Nobeyama 45m radio telescope. Accurate radial velocities were
obtained for 229 (220 new) detected stars. The sample is selected from optical
variables found by new automated surveys: the Northern Sky Variability Survey
and the All Sky Automated Survey. The new sample consists of the "bluer"
objects compared with those observed in the previous SiO surveys. The distances
to the objects are estimated using the period-luminosity relation, and they are
mostly less than 3 kpc from the Sun. The longitude-velocity diagram reveals
three prominent groups of stars deviant from the circular Galactic rotation
with a flat rotation curve. In addition to the Hercules group of stars which
was studied before, we found two new deviant groups: one toward the Perseus arm
and the other toward the Sagittarius arm. These two groups both exhibit
anomalous motions toward the Galactic center, which seem to be consistent with
the noncircular motions of these spiral arms found in the recent VLBI
proper-motion measurements for maser gas clumps.Comment: PASJ 64 no.1 (2012 Feb. 25 issue) in press. A full version including
Fig. 8a-m, and Fig. 9 are available at
http://www.nro.nao.ac.jp/~lib_pub/report/data/no680.pd
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