Electric-Field-Induced Resonant Spin Polarization in a Two-Dimensional Electron Gas

Electric response of spin polarization in two-dimensional electron gas with structural inversion asymmetry subjected to a magnetic field was studied by means of the linear and non-linear theory and numerical simulation with the disorder effect. It was found by Kubo linear reponse theory that an electric resonant response of spin polarization occurs when the Fermi surface is located near the crossing of two Landau levels, which is induced from the competition between the spin-orbit coupling and Zeeman splitting. The scaling behavior was investigated with a simplified two-level model by non-linear method, and the resonant peak value is reciprocally proportional to the electric field at low temperatures and to temperature for finite electric fields. Finally numerical simulation illustrated that impurity potential opens an enegy gap near the resonant point and suppresses the effect gradually with the increasing strength of disorder. This resonant effect may provide an efficient way to control spin polarization by an external electric field.Comment: 6 pages, 5 figure

Particle Filters for Markov Switching Stochastic Volatility Models

This paper proposes an auxiliary particle filter algorithm for inference in regime switching stochastic volatility models in which the regime state is governed by a first-order Markov chain. We proposes an ongoing updated Dirichlet distribution to estimate the transition probabilities of the Markov chain in the auxiliary particle filter. A simulation-based algorithm is presented for the method which demonstrated that we are able to estimate a class of models in which the probability that the system state transits from one regime to a different regime is relatively high. The methodology is implemented to analyze a real time series: the foreign exchange rate of Australian dollars vs South Korean won.Particle filters; Markov switching stochastic volatility models; Sequential Monte Carlo simulation

Titanium dioxide photocatalytic degradation of organophosphonates

The titanium dioxide mediated photocatalytic degradation of dimethyl phenylphosphonate (DMPP) has been investigated. DMPP can be completely decomposed by irradiation of an aqueous suspension of Ti02 in the presence of oxygen, though the total mineralization of organophosphonates takes longer than the complete decomposition of dimethyl phenylphosphonate. DMPP degrades faster at higher pH values and lower initial concentrations. The photocatalytic degradation reaction can be described by the first order kinetics. The product distribution, the effect of different substituents on the phenyl ring, the similarity of the initial products obtained from the Ti02 photocatalytic degradation and H202 photolysis indicate that the chemistry of photocatalytic degradation of dimethyl phenylphosphonate at the early stages is consistent with hydroxyl radical chemistry. A mechanistic study of the degradation of 180-labeled DMPP indicates that an addition-elimination mechanism is not likely for the demethylation step during the photocatalytic degradation process

Enhanced Feedback Iterative Decoding of Sparse Quantum Codes

Decoding sparse quantum codes can be accomplished by syndrome-based decoding using a belief propagation (BP) algorithm.We significantly improve this decoding scheme by developing a new feedback adjustment strategy for the standard BP algorithm. In our feedback procedure, we exploit much of the information from stabilizers, not just the syndrome but also the values of the frustrated checks on individual qubits of the code and the channel model. Furthermore we show that our decoding algorithm is superior to belief propagation algorithms using only the syndrome in the feedback procedure for all cases of the depolarizing channel. Our algorithm does not increase the measurement overhead compared to the previous method, as the extra information comes for free from the requisite stabilizer measurements.Comment: 10 pages, 11 figures, Second version, To be appeared in IEEE Transactions on Information Theor