1,828 research outputs found
Determination of the Sign of g factors for Conduction Electrons Using Time-resolved Kerr Rotation
The knowledge of electron g factor is essential for spin manipulation in the
field of spintronics and quantum computing. While there exist technical
difficulties in determining the sign of g factor in semiconductors by the
established magneto-optical spectroscopic methods. We develop a time resolved
Kerr rotation technique to precisely measure the sign and the amplitude of
electron g factor in semiconductors
Speculation and Volatility Spillover in the Crude Oil and Agricultural Commodity Markets: A Bayesian Analysis
This paper assesses the roles of various factors influencing the volatility of crude oil prices and the possible linkage between this volatility and agricultural commodity markets. Stochastic volatility models are applied to weekly crude oil, corn and wheat futures prices from November 1998 to January 2009. Model parameters are estimated using Bayesian Markov chain Monte Carlo methods. The main results are as follows. Speculation, scalping, and petroleum inventories are found to be important in explaining oil price variation. Several properties of crude oil price dynamics are established including mean-reversion, a negative correlation between price and volatility, volatility clustering, and infrequent compound Poisson jumps. We find evidence of volatility spillover among crude oil, corn and wheat markets after the fall of 2006. This could be largely explained by tightened interdependence between these markets induced by ethanol production.Gibbs sampling, Merton jump, leverage effect, stochastic volatility, Demand and Price Analysis, Financial Economics, Resource /Energy Economics and Policy, G13, Q4,
Are Crop Yield Distributions Negatively Skewed? A Bayesian Examination
Crop Production/Industries,
Fast initialization of the spin state of an electron in a quantum dot in the Voigt configuration
We consider the initialization of the spin-state of a single electron trapped
in a self-assembled quantum dot via optical pumping of a trion level. We show
that with a magnetic field applied perpendicular to the growth direction of the
dot, a near-unity fidelity can be obtained in a time equal to a few times the
inverse of the spin-conserving trion relaxation rate. This method is several
orders-of-magnitude faster than with the field aligned parallel, since this
configuration must rely on a slow hole spin-flip mechanism. This increase in
speed does result in a limit on the maximum obtainable fidelity, but we show
that for InAs dots, the error is very small.Comment: 4 pages, 4 figure
Optimal phase space projection for noise reduction
In this communication we will re-examine the widely studied technique of
phase space projection. By imposing a time domain constraint (TDC) on the
residual noise, we deduce a more general version of the optimal projector,
which includes those appearing in previous literature as subcases but does not
assume the independence between the clean signal and the noise. As an
application, we will apply this technique for noise reduction. Numerical
results show that our algorithm has succeeded in augmenting the signal-to-noise
ratio (SNR) for simulated data from the R\"ossler system and experimental
speech record.Comment: Accepted version for PR
Loss Enhanced Transmission and Collimation in Anisotropic Epsilon-Near-Zero Metamaterials
We verify the extraordinary transmission enhancement and collimation induced by the material loss in anisotropic epsilon-near-zero metamaterials, and reveal the physical mechanism of this exotic electromagnetic phenomenon via the iso-frequency contour analysis. In addition, we demonstrate the possibility in realization of such loss enhanced transmission of Gaussian beam in realistic silver-germanium multilayered structures by applying full-wave numerical simulations
Optical Nonlocality Induced Zitterbewegung near the Dirac Point in Metal-Dielectric Multilayer Metamaterials
Fast spin rotations by optically controlled geometric phases in a quantum dot
We demonstrate optical control of the geometric phase acquired by one of the
spin states of an electron confined in a charge-tunable InAs quantum dot via
cyclic 2pi excitations of an optical transition in the dot. In the presence of
a constant in-plane magnetic field, these optically induced geometric phases
result in the effective rotation of the spin about the magnetic field axis and
manifest as phase shifts in the spin quantum beat signal generated by two
time-delayed circularly polarized optical pulses. The geometric phases
generated in this manner more generally perform the role of a spin phase gate,
proving potentially useful for quantum information applications.Comment: 4 pages, 3 figures, resubmitted to Physical Review Letter
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