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Taro Ando

Publications and source records attributed to Taro Ando.

2 recordsLinked to original sources

Numerical method for coherent electron dynamics with position-dependent effective-mass distributions in semiconductor heterostructures.

We develop a numerical scheme for solving the time-dependent Kohn-Sham equation in semiconductor heterostructures. Based on the efficient and accurate method recently proposed by Watanabe and Tsukada [Phys. Rev. E 65, 036705 (2002)], an extension is made for treating effective-mass mismatch between different semiconductor materials. A demonstrative calculation shows that the energy of the quantum-well state is accurately conserved during the time-evolution calculation with the present method. Examples under the existence of Hartree and exchange-correlation interactions are also shown as demonstrations of nonlinear electron dynamics in quantum wells. The present method is particularly useful for analyzing nonlinear coherent charge oscillations in semiconductor quantum wells, taking into account many-body effects.

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Femtosecond pulse propagation in nitrogen: numerical study of (3 + 1)-dimensional extended nonlinear Schrödinger equation with shock-term correction.

We develop an accurate and efficient method for calculating evolution due to the extended nonlinear Schrödinger equation, which describes the propagation behavior of a femtosecond light pulse in a nonlinear medium. Applying Suzuki's exponential operator expansion to the evolution operator based on the finite-differential formulation, we realize the accurate and fast calculation that can be performed without large-scale computing systems even for (3 + 1)-dimensional problems. To study the correspondence between experiments and calculations, we calculate the propagation behavior of a femtosecond light pulse that is weakly focused in nitrogen gas of various pressures and compare the calculation results to the experimental ones. The calculation results reproduce the relative behavior of the spatial light pattern observed during the propagation. Additionally, the multiple-cone formation and interaction between two collimated pulses in nitrogen gas are also demonstrated as applications of the developed method.

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