The Experts below are selected from a list of 115536 Experts worldwide ranked by ideXlab platform
Yoshitaka Tanimura - One of the best experts on this subject based on the ideXlab platform.
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dephasing by a continuous time random walk process
Physical Review E, 2012Co-Authors: Daniel M Packwood, Yoshitaka TanimuraAbstract:Stochastic treatments of magnetic resonance spectroscopy and optical spectroscopy require evaluations of functions such as $\ensuremath{\langle}\mathrm{exp}(i{\ensuremath{\int}}_{0}^{t}{Q}_{s}ds)\ensuremath{\rangle}$, where $t$ is time, ${Q}_{s}$ is the value of a stochastic process at time $s$, and the angular brackets denote ensemble averaging. This paper gives an exact evaluation of these functions for the case where $Q$ is a continuous-time random walk process. The continuous-time random walk describes an environment that undergoes slow steplike changes in time. It also has a well-defined Gaussian limit and so allows for non-Gaussian and Gaussian stochastic dynamics to be studied within a single framework. We apply the results to extract qubit-lattice interaction parameters from dephasing data of $P$-doped Si semiconductors (data collected elsewhere) and to calculate the two-Dimensional Spectrum of a three-level harmonic oscillator undergoing random frequency modulations.
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Dephasing by a continuous-time random walk process.
Physical review. E Statistical nonlinear and soft matter physics, 2012Co-Authors: Daniel M Packwood, Yoshitaka TanimuraAbstract:Stochastic treatments of magnetic resonance spectroscopy and optical spectroscopy require evaluations of functions such as (exp(i ∫(0)(t) Q(s)ds)), where t is time, Q(s) is the value of a stochastic process at time s, and the angular brackets denote ensemble averaging. This paper gives an exact evaluation of these functions for the case where Q is a continuous-time random walk process. The continuous-time random walk describes an environment that undergoes slow steplike changes in time. It also has a well-defined Gaussian limit and so allows for non-Gaussian and Gaussian stochastic dynamics to be studied within a single framework. We apply the results to extract qubit-lattice interaction parameters from dephasing data of P-doped Si semiconductors (data collected elsewhere) and to calculate the two-Dimensional Spectrum of a three-level harmonic oscillator undergoing random frequency modulations.
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Probing a colored-noise induced peak of a strongly damped Brownian system by one- and two-Dimensional spectroscopy
Chemical Physics Letters, 2002Co-Authors: Yoko Suzuki, Yoshitaka TanimuraAbstract:When dynamics of a system strongly coupled to a white-noise environment is overdamped, in linear spectroscopy, the Spectrum is observed as one peak near zero vibrational frequency. We found, however, that if the noise induced by the environment is colored and its correlation time is long, there is an additional peak at a frequency different from the system. We study the multi-Dimensional Spectrum, to observe the interplay between the overdamped motion and the weakly damped motion induced by the colored noise. Finally, we discuss the connection between the peak due to the colored noise and the Boson peak found in glass materials and supercooled liquids.
Daniel M Packwood - One of the best experts on this subject based on the ideXlab platform.
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dephasing by a continuous time random walk process
Physical Review E, 2012Co-Authors: Daniel M Packwood, Yoshitaka TanimuraAbstract:Stochastic treatments of magnetic resonance spectroscopy and optical spectroscopy require evaluations of functions such as $\ensuremath{\langle}\mathrm{exp}(i{\ensuremath{\int}}_{0}^{t}{Q}_{s}ds)\ensuremath{\rangle}$, where $t$ is time, ${Q}_{s}$ is the value of a stochastic process at time $s$, and the angular brackets denote ensemble averaging. This paper gives an exact evaluation of these functions for the case where $Q$ is a continuous-time random walk process. The continuous-time random walk describes an environment that undergoes slow steplike changes in time. It also has a well-defined Gaussian limit and so allows for non-Gaussian and Gaussian stochastic dynamics to be studied within a single framework. We apply the results to extract qubit-lattice interaction parameters from dephasing data of $P$-doped Si semiconductors (data collected elsewhere) and to calculate the two-Dimensional Spectrum of a three-level harmonic oscillator undergoing random frequency modulations.
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Dephasing by a continuous-time random walk process.
Physical review. E Statistical nonlinear and soft matter physics, 2012Co-Authors: Daniel M Packwood, Yoshitaka TanimuraAbstract:Stochastic treatments of magnetic resonance spectroscopy and optical spectroscopy require evaluations of functions such as (exp(i ∫(0)(t) Q(s)ds)), where t is time, Q(s) is the value of a stochastic process at time s, and the angular brackets denote ensemble averaging. This paper gives an exact evaluation of these functions for the case where Q is a continuous-time random walk process. The continuous-time random walk describes an environment that undergoes slow steplike changes in time. It also has a well-defined Gaussian limit and so allows for non-Gaussian and Gaussian stochastic dynamics to be studied within a single framework. We apply the results to extract qubit-lattice interaction parameters from dephasing data of P-doped Si semiconductors (data collected elsewhere) and to calculate the two-Dimensional Spectrum of a three-level harmonic oscillator undergoing random frequency modulations.
Philippe Bolon - One of the best experts on this subject based on the ideXlab platform.
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2-Dimensional Wavelet Packet Spectrum for Texture Analysis
IEEE Transactions on Image Processing, 2013Co-Authors: Abdourrahmane Atto, Yannick Berthoumieu, Philippe BolonAbstract:The paper derives a 2-Dimensional Spectrum estimator from some recent results on the statistical properties of wavelet packet coefficients of random processes. It provides an analysis of the bias of this estimator with respect to the wavelet order. The paper also discusses the performance of this wavelet based estimator, in comparison with the conventional 2-D Fourier-based Spectrum estimator on texture analysis and content based image retrieval. It highlights the effectiveness of the wavelet based Spectrum estimation.
Borries Demeler - One of the best experts on this subject based on the ideXlab platform.
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A two-Dimensional Spectrum analysis for sedimentation velocity experiments of mixtures with heterogeneity in molecular weight and shape
European Biophysics Journal, 2010Co-Authors: Emre Brookes, Borries DemelerAbstract:We report a model-independent analysis approach for fitting sedimentation velocity data which permits simultaneous determination of shape and molecular weight distributions for mono- and polydisperse solutions of macromolecules. Our approach allows for heterogeneity in the frictional domain, providing a more faithful description of the experimental data for cases where frictional ratios are not identical for all components. Because of increased accuracy in the frictional properties of each component, our method also provides more reliable molecular weight distributions in the general case. The method is based on a fine grained two-Dimensional grid search over s and f/f _0, where the grid is a linear combination of whole boundary models represented by finite element solutions of the Lamm equation with sedimentation and diffusion parameters corresponding to the grid points. A Monte Carlo approach is used to characterize confidence limits for the determined solutes. Computational algorithms addressing the very large memory needs for a fine grained search are discussed. The method is suitable for globally fitting multi-speed experiments, and constraints based on prior knowledge about the experimental system can be imposed. Time- and radially invariant noise can be eliminated. Serial and parallel implementations of the method are presented. We demonstrate with simulated and experimental data of known composition that our method provides superior accuracy and lower variance fits to experimental data compared to other methods in use today, and show that it can be used to identify modes of aggregation and slow polymerization.
Steven T Cundiff - One of the best experts on this subject based on the ideXlab platform.
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frequency comb based double quantum two Dimensional Spectrum identifies collective hyperfine resonances in atomic vapor induced by dipole dipole interactions
Physical Review Letters, 2018Co-Authors: Bachana Lomsadze, Steven T CundiffAbstract:Frequency comb based multiDimensional coherent spectroscopy is a novel optical method that enables high resolution measurement in a short acquisition time. The method's resolution makes multiDimensional coherent spectroscopy relevant for atomic systems that have narrow resonances. We use double-quantum multiDimensional coherent spectroscopy to reveal collective hyperfine resonances in rubidium vapor at 100 C induced by dipole-dipole interactions. We observe tilted lineshapes in the double-quantum 2D spectra, which has never been reported for Doppler-broadened systems. The tilted lineshapes suggest that the signal is predominately from the interacting atoms that have near zero relative velocity.
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frequency comb based double quantum two Dimensional Spectrum identifies collective hyperfine resonances in atomic vapor induced by dipole dipole interactions
Physical Review Letters, 2018Co-Authors: Bachana Lomsadze, Steven T CundiffAbstract:Frequency-comb based multiDimensional coherent spectroscopy is a novel optical method that enables high-resolution measurement in a short acquisition time. The method's resolution makes multiDimensional coherent spectroscopy relevant for atomic systems that have narrow resonances. We use double-quantum multiDimensional coherent spectroscopy to reveal collective hyperfine resonances in rubidium vapor at $100\text{ }\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ induced by dipole-dipole interactions. We observe tilted and elongated line shapes in the double-quantum 2D spectra, which have never been reported for Doppler-broadened systems. The elongated line shapes suggest that the signal is predominately from the interacting atoms that have a near zero relative velocity.