32,629 research outputs found
Heisenberg-picture approach to the exact quantum motion of a time-dependent forced harmonic oscillator
In the Heisenberg picture, the generalized invariant and exact quantum
motions are found for a time-dependent forced harmonic oscillator. We find the
eigenstate and the coherent state of the invariant and show that the
dispersions of these quantum states do not depend on the external force. Our
formalism is applied to several interesting cases.Comment: 15 pages, two eps files, to appear in Phys. Rev. A 53 (6) (1996
Reactor Fuel Fraction Information on the Antineutrino Anomaly
We analyzed the evolution data of the Daya Bay reactor neutrino experiment in
terms of short-baseline active-sterile neutrino oscillations taking into
account the theoretical uncertainties of the reactor antineutrino fluxes. We
found that oscillations are disfavored at with respect to a
suppression of the reactor antineutrino flux and at
with respect to variations of the and
fluxes. On the other hand, the analysis of the rates of the
short-baseline reactor neutrino experiments favor active-sterile neutrino
oscillations and disfavor the suppression of the flux at
and variations of the and fluxes
at . We also found that both the Daya Bay evolution data and the
global rate data are well-fitted with composite hypotheses including variations
of the or fluxes in addition to
active-sterile neutrino oscillations. A combined analysis of the Daya Bay
evolution data and the global rate data shows a slight preference for
oscillations with respect to variations of the and
fluxes. However, the best fits of the combined data are given
by the composite models, with a preference for the model with an enhancement of
the flux and relatively large oscillations.Comment: 9 page
Electrical Control of Dynamic Spin Splitting Induced by Exchange Interaction as Revealed by Time Resolved Kerr Rotation in a Degenerate Spin-Polarized Electron Gas
The manipulation of spin degree of freedom have been demonstrated in spin
polarized electron plasma in a heterostructure by using exchange-interaction
induced dynamic spin splitting rather than the Rashba and Dresselhaus types, as
revealed by time resolved Kerr rotation. The measured spin splitting increases
from 0.256meV to 0.559meV as the bias varies from -0.3V to -0.6V. Both the sign
switch of Kerr signal and the phase reversal of Larmor precessions have been
observed with biases, which all fit into the framework of
exchange-interaction-induced spin splitting. The electrical control of it may
provide a new effective scheme for manipulating spin-selected transport in spin
FET-like devices.Comment: 8 pages, 3 figures ; added some discussion
Spin Dynamics in the Second Subband of a Quasi Two Dimensional System Studied in a Single Barrier Heterostructure by Time Resolved Kerr Rotation
By biasing a single barrier heterostructure with a 500nm-thick GaAs layer as
the absorption layer, the spin dynamics for both of the first and second
subband near the AlAs barrier are examined. We find that when simultaneously
scanning the photon energy of both the probe and pump beams, a sign reversal of
the Kerr rotation (KR) takes place as long as the probe photons break away the
first subband and probe the second subband. This novel feature, while stemming
from the exchange interaction, has been used to unambiguously distinguish the
different spin dynamics ( and ) for the first and second
subbands under the different conditions by their KR signs (negative for
and positive for ). In the zero magnetic field, by scanning
the wavelength towards the short wavelength, decreases in accordance
with the D'yakonov-Perel' (DP) spin decoherence mechanism. At 803nm,
(450ps) becomes ten times longer than (50ps). However, the
value of at 803nm is roughly the same as the value of at
815nm. A new feature has been disclosed at the wavelength of 811nm under the
bias of -0.3V (807nm under the bias of -0.6V) that the spin coherence times
( and ) and the effective factors ( and
) all display a sudden change, due to the "resonant" spin exchange
coupling between two spin opposite bands.Comment: 9pages, 3 figure
Spin dynamics and magnetic interactions of Mn dopants in the topological insulator BiTe
The magnetic and electronic properties of the magnetically doped topological
insulator BiMnTe were studied using electron spin
resonance (ESR) and measurements of static magnetization and electrical
transport. The investigated high quality single crystals of BiMnTe show a ferromagnetic phase transition for
at K. The Hall measurements reveal a p-type finite
charge-carrier density. Measurements of the temperature dependence of the ESR
signal of Mn dopants for different orientations of the external magnetic field
give evidence that the localized Mn moments interact with the mobile charge
carriers leading to a Ruderman-Kittel-Kasuya-Yosida-type ferromagnetic coupling
between the Mn spins of order 2-3 meV. Furthermore, ESR reveals a
low-dimensional character of magnetic correlations that persist far above the
ferromagnetic ordering temperature
Non-Abelian Medium Effects in Quark-Gluon Plasma
Based on the kinetic theory, the non-Abelian medium property of hot
Quark-Gluon Plasma is investigated. The nonlinearity of the plasma comes from
two aspects: The nonlinear wave-wave interaction and self-interaction of color
field. The non-Abelian color permittivity is obtained by expanding the kinetic
equations to third order. As an application, the nonlinear Landau damping rate
and the nonlinear eigenfrequency shift are calculated in the longwave length
limit.Comment: 12 pages(Revtex), no figure
Presynaptic protein synthesis required for NT-3-induced long-term synaptic modulation
10.1186/1756-6606-4-1Molecular Brain41
Topology of Knotted Optical Vortices
Optical vortices as topological objects exist ubiquitously in nature. In this
paper, by making use of the -mapping topological current theory, we
investigate the topology in the closed and knotted optical vortices. The
topological inner structure of the optical vortices are obtained, and the
linking of the knotted optical vortices is also given.Comment: 11 pages, no figures, accepted by Commun. Theor. Phys. (Beijing, P.
R. China
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