The Experts below are selected from a list of 138963 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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open quantum dynamics of a three dimensional rotor calculated using a rotationally Invariant System bath hamiltonian linear and two dimensional rotational spectra
Journal of Chemical Physics, 2019Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear rigid rotor independently coupled to three harmonic-oscillator baths through functions of the rotor’s Euler angles. While this model has been developed to study the dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics. Specifically, the treatment presented here is carried out as an extension of a previous work [Y. Iwamoto and Y. Tanimura, J. Chem. Phys 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Leggett model. To illustrate the characteristic features of the quantum 3D rotor System described by angular momentum and magnetic quantum numbers, we derive a quantum master equation (QME) and hierarchical equations of motion for the 3D RISB model in the high-temperature case. Using the QME, we compute linear and 2D rotational spectra defined by the linear and nonlinear response functions of the rotor dipole, respectively. The quantum transitions between the angular momentum states and magnetic states arising from polarized Stark fields as well as the System-bath interactions can be clearly observed in 2D rotational spectroscopy.We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear rigid rotor independently coupled to three harmonic-oscillator baths through functions of the rotor’s Euler angles. While this model has been developed to study the dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics. Specifically, the treatment presented here is carried out as an extension of a previous work [Y. Iwamoto and Y. Tanimura, J. Chem. Phys 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Leggett model. To illustrate the characteristic features of the quantum 3D rotor System described by angular momen...
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open quantum dynamics of a three dimensional rotor calculated using a rotationally Invariant System bath hamiltonian linear and two dimensional rotational spectra
arXiv: Statistical Mechanics, 2019Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear-rigid rotor independently coupled to three sets of harmonic-oscillator baths as functions of the Euler angle. While this model has been developed to study a dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics as an extension of our previous work [J. Chem. Phys, 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Legget (RCL) model. To illustrate characteristic features of the quantum 3D rotor System described by angular momentum and magnetic quantum numbers, we derive a quantum master equation (QME) and hierarchical equations of motion (HEOM) for the 3D RISB model in the high-temperature case. Using the QME, we compute linear and two-dimensional (2D) rotational spectra, defined by the linear and nonlinear response functions of the rotor dipole, respectively. The quantum transitions between the angular momentum states and magnetic states arising from polarized Stark fields as well as the System-bath interactions are clearly observed in 2D rotational spectroscopy.
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linear absorption spectrum of a quantum two dimensional rotator calculated using a rotationally Invariant System bath hamiltonian
Journal of Chemical Physics, 2018Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a two-dimensional rigid rotator System coupled to a two-dimensional heat bath. The Caldeira-Leggett (Brownian) model for the rotator and the spin-Boson model have been used to describe such Systems, but they do not possess rotational symmetry, and they cannot describe the discretized rotational bands in absorption and emission spectra that have been found experimentally. Here, to address this problem, we introduce a rotationally Invariant System-bath (RISB) model that is described by two sets of harmonic-oscillator baths independently coupled to the rigid rotator as sine and cosine functions of the rotator angle. Due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the RISB model differ significantly from those described by the rotational Caldeira-Legget model, while both models reduce to the Langevin equation for a rotator in the classical limit. To demonstrate this point, we compute the rotational absorption spectrum defined by the linear response function of a rotator dipole. For this purpose, we derive a quantum master equation for the RISB model in the high-temperature Markovian case. We find that the spectral profiles of the calculated signals exhibit a transition from quantized rotational bands to a single peak after spectrum collapse. This is a significant finding because previous approaches cannot describe such phenomena in a unified manner.
Yuki Iwamoto - One of the best experts on this subject based on the ideXlab platform.
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open quantum dynamics of a three dimensional rotor calculated using a rotationally Invariant System bath hamiltonian linear and two dimensional rotational spectra
Journal of Chemical Physics, 2019Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear rigid rotor independently coupled to three harmonic-oscillator baths through functions of the rotor’s Euler angles. While this model has been developed to study the dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics. Specifically, the treatment presented here is carried out as an extension of a previous work [Y. Iwamoto and Y. Tanimura, J. Chem. Phys 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Leggett model. To illustrate the characteristic features of the quantum 3D rotor System described by angular momentum and magnetic quantum numbers, we derive a quantum master equation (QME) and hierarchical equations of motion for the 3D RISB model in the high-temperature case. Using the QME, we compute linear and 2D rotational spectra defined by the linear and nonlinear response functions of the rotor dipole, respectively. The quantum transitions between the angular momentum states and magnetic states arising from polarized Stark fields as well as the System-bath interactions can be clearly observed in 2D rotational spectroscopy.We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear rigid rotor independently coupled to three harmonic-oscillator baths through functions of the rotor’s Euler angles. While this model has been developed to study the dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics. Specifically, the treatment presented here is carried out as an extension of a previous work [Y. Iwamoto and Y. Tanimura, J. Chem. Phys 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Leggett model. To illustrate the characteristic features of the quantum 3D rotor System described by angular momen...
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open quantum dynamics of a three dimensional rotor calculated using a rotationally Invariant System bath hamiltonian linear and two dimensional rotational spectra
arXiv: Statistical Mechanics, 2019Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a rotationally Invariant System-bath (RISB) model in three-dimensional space that is described by a linear-rigid rotor independently coupled to three sets of harmonic-oscillator baths as functions of the Euler angle. While this model has been developed to study a dielectric relaxation of a dipolar molecule in solvation as a problem of classical Debye relaxation, here we investigate it as a problem of open quantum dynamics as an extension of our previous work [J. Chem. Phys, 149, 084110 (2018)], in which we studied a two-dimensional (2D) RISB model, to a three-dimensional (3D) RISB model. As in the 2D case, due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the 3D RISB model differ significantly from those described by the rotational Caldeira-Legget (RCL) model. To illustrate characteristic features of the quantum 3D rotor System described by angular momentum and magnetic quantum numbers, we derive a quantum master equation (QME) and hierarchical equations of motion (HEOM) for the 3D RISB model in the high-temperature case. Using the QME, we compute linear and two-dimensional (2D) rotational spectra, defined by the linear and nonlinear response functions of the rotor dipole, respectively. The quantum transitions between the angular momentum states and magnetic states arising from polarized Stark fields as well as the System-bath interactions are clearly observed in 2D rotational spectroscopy.
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linear absorption spectrum of a quantum two dimensional rotator calculated using a rotationally Invariant System bath hamiltonian
Journal of Chemical Physics, 2018Co-Authors: Yuki Iwamoto, Yoshitaka TanimuraAbstract:We consider a two-dimensional rigid rotator System coupled to a two-dimensional heat bath. The Caldeira-Leggett (Brownian) model for the rotator and the spin-Boson model have been used to describe such Systems, but they do not possess rotational symmetry, and they cannot describe the discretized rotational bands in absorption and emission spectra that have been found experimentally. Here, to address this problem, we introduce a rotationally Invariant System-bath (RISB) model that is described by two sets of harmonic-oscillator baths independently coupled to the rigid rotator as sine and cosine functions of the rotator angle. Due to a difference in the energy discretization of the total Hamiltonian, the dynamics described by the RISB model differ significantly from those described by the rotational Caldeira-Legget model, while both models reduce to the Langevin equation for a rotator in the classical limit. To demonstrate this point, we compute the rotational absorption spectrum defined by the linear response function of a rotator dipole. For this purpose, we derive a quantum master equation for the RISB model in the high-temperature Markovian case. We find that the spectral profiles of the calculated signals exhibit a transition from quantized rotational bands to a single peak after spectrum collapse. This is a significant finding because previous approaches cannot describe such phenomena in a unified manner.
Luca Zaccarian - One of the best experts on this subject based on the ideXlab platform.
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stubborn state observers for linear time Invariant Systems
Automatica, 2018Co-Authors: Angelo Alessandri, Luca ZaccarianAbstract:For the purpose of estimating the state of a linear time-Invariant System with measurements subject to outliers, we propose an observer with a saturated output injection in such a way to mitigate the effect of abnormal and isolated measurement noise on the error dynamics. Stability conditions in both the continuous-time and the discrete-time cases are derived, which ensure global exponential stability to the origin for the error dynamics. Such conditions can be expressed in terms of linear matrix inequalities, allowing for a viable design by using convex optimization. The effectiveness of the approach is illustrated by means of simulations in comparison with the Luenberger observer.
Rajendra Prasad - One of the best experts on this subject based on the ideXlab platform.
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a new technique for reduced order modelling of linear time Invariant System
Iete Journal of Research, 2017Co-Authors: Afzal Sikander, Rajendra PrasadAbstract:ABSTRACTIn this paper, a new technique for order reduction of linear time-Invariant Systems is presented. This technique is intended for both single-input single-output (SISO) and multi-input multi-output (MIMO) Systems. Motivated by other reduction techniques, the new proposed reduction technique is based on modified pole clustering and factor division algorithm with the objective of obtaining a stable reduced-order System preserving all essential properties of the original System. The new technique is illustrated by three numerical examples which are considered from the literature. To evaluate the superiority and robustness of the new technique, the results of the proposed technique are compared with other well-known and recently developed order-reduction techniques like Routh approximation and Big Bang-Big Crunch algorithm. The comparison of performance indices shows the efficiency and powerfulness of the new technique.
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linear time Invariant System reduction using a mixed methods approach
Applied Mathematical Modelling, 2015Co-Authors: Afzal Sikander, Rajendra PrasadAbstract:Abstract In this study, we propose a new method for obtaining a reduced order model of high order linear time-Invariant single input–single output (SISO) and multiple input–multiple output (MIMO) Systems, which is based on the stability equation method and factor division algorithm. For a given higher order linear time-Invariant System, the coefficients of the numerator polynomial are estimated by the factor division algorithm while the coefficients of the denominator polynomial are calculated by the stability equation method. The distinctive feature of the proposed method is that the reduced model will always be stable if the original System is stable. Numerical examples are provided that demonstrate the superior performance of the proposed method compared with other well-known published methods.
Anton Ponomarev - One of the best experts on this subject based on the ideXlab platform.
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reduction based robustness analysis of linear predictor feedback for distributed input delays
IEEE Transactions on Automatic Control, 2016Co-Authors: Anton PonomarevAbstract:Lyapunov–Krasovskii approach is applied to parameter-robustness and delay-robustness analysis of the feedback suggested by Manitius and Olbrot for a linear time-Invariant System with distributed input delay. A functional is designed based on Artstein's System reduction technique. It depends on the norms of the reduction-transformed plant state and original actuator state. The functional is used to prove that the feedback is stabilizing when there is a slight mismatch in the System matrices and delay values between the plant and controller.
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reduction based robustness analysis of linear predictor feedback for distributed input delays
arXiv: Optimization and Control, 2015Co-Authors: Anton PonomarevAbstract:Lyapunov-Krasovskii approach is applied to parameter- and delay-robustness analysis of the feedback suggested by Manitius and Olbrot for a linear time-Invariant System with distributed input delay. A functional is designed based on Artstein's System reduction technique. It depends on the norms of the reduction-transformed plant state and original actuator state. The functional is used to prove that the feedback is stabilizing when there is a slight mismatch in the System matrices and delay values between the plant and controller.
