17,772 research outputs found
Multifractal detrended cross-correlation analysis for two nonstationary signals
It is ubiquitous in natural and social sciences that two variables, recorded
temporally or spatially in a complex system, are cross-correlated and possess
multifractal features. We propose a new method called multifractal detrended
cross-correlation analysis (MF-DXA) to investigate the multifractal behaviors
in the power-law cross-correlations between two records in one or higher
dimensions. The method is validated with cross-correlated 1D and 2D binomial
measures and multifractal random walks. Application to two financial time
series is also illustrated.Comment: 4 RevTex pages including 6 eps figure
Electronic structure and superconductivity of BiS2-based compounds LaO1-xFxBiS2
Using the density-functional perturbation theory with structural
optimization, we investigate the electronic structure, phonon spectra, and
superconductivity of BiS2-based layered compounds LaO1-xFxBiS2. For
LaO0.5F0.5BiS2, the calculated electron-phonon coupling constant is equal to
lambda = 0.8, and obtained Tc = 9.1 K is very close to its experimental value,
indicating that it is a conventional electron-phonon superconductor
Double quantum dot as detector of spin bias
It was proposed that a double quantum dot can be used to be a detector of
spin bias. Electron transport through a double quantum dot is investigated
theoretically when a pure spin bias is applied on two conducting leads
contacted to the quantum dot. It is found that the spin polarization in the
left and right dots may be induced spontaneously while the intra-dot levels are
located within the spin bias window and breaks the left-right symmetry of the
two quantum dots. As a result, a large current emerges. For an open external
circuit an charge bias instead of a charge current will be induced in
equilibrium, which is believed to be measurable according to the current
nanotechnology. This method may provide a practical and whole electrical
approach to detect the spin bias (or the spin current) by measuring the charge
bias or current in a double quantum dot.Comment: 13 pages, 5 figure
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