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Quantum decoherence in an electron-phonon composite system
[Experiment] Decoherence process in semiconductors (GaAs crystal and multiple quantum well (MQW) structures) has been studied by the ultrafast quantum path interferometry using relative phase-locked femtosecond optical pulses.
[Theory] Ultrafast dynamics in an electron-phonon composite system is studied using a simple quantum model (two-level system and harmonic oscillators) and the quantum master equation.
電子フォノン複合系における量子コヒーレンス
[実験] 半導体(GaAs結晶と多重量子井戸構造)におけるデコヒーレンス過程を、相対位相制御したフェムト秒光パルスを用いた超高速量子経路干渉を用いて、研究しています。
[理論] 電子フォノン複合系の超高速ダイナミクスをシンプルな量子モデル(2準位電子系と調和振動子フォノン)と量子マスター方程式を用いて研究しています。
I. Takagi, Y. Konno, Y. Kayanuma, and K. G. Nakamura: Dual role of longitudinal optical phonons for generation of coherent oscillations in gallium arsenide, Phys. Rev. B 110, 024314 (2024). (Editor's Suggestion)
I. Takagi, Y. Kayanuma, and K. G. Nakamura: Ultrafast quantum path interferometry to determine the electronic decoherence time of the electron-phonon coupled system in n-type gallium arsenide, Phys. Rev. B 107, 184305 (2023).
Y. Furusyo, R. Yagi, M. Suda, I. Tagkagi, T. Maruhashi, Y. Kayanuma, F. Minami, and K. G. Nakamura: Ultrafast quantum-path interferometry og photo-absorption involiving excitons in a GaAs multiple-quantum well structure, Solid State Commun., 369, 115056 (2023).
K. G. Nakamura, K. Yokota, Y. Okuda, R. Kase, T. Kitashima, Y. Shikano, and Y. Kayanuma, Phys. Rev. B 99, 180301(R) (2019). (Editor's Suggestion).
Ultrafast dynamics of phonons in carbon materials
Ultrafast dynamics of phonons in carbon materials (diamond, graphite, glassy carbon, and ion-irradiated graphite) is studied with transient reflectivity measurements in connection with investigation of carbon support for catalysis.
炭素系物質のフォノンの超高速ダイナミクス
炭素系物質(ダイヤモンド、グラファイト、ガラス状炭素、イオン照射グラファイト)におけるフォノンの超高速ダイナミクスを過渡反射率計測を用いて研究しています。この研究は触媒の炭素担体機能の研究にも関連した課題です。
T. Kimata, T. Kato, I. Takagi, Y. Konno, H. Okazaki, S. Yamamoto, T. Yamaki, and K. G. Nakamura: 380-keV Ar+ irradiation effects on optical phonons in graphite studied with transient reflection measurement, J. Appl. Phys., 134, 135306 (2023).
I. Takagi, T. Kimata, Y. Konno, and K. G. Nakamura: Coherent optical phonons in glassy carbon, Carbon 204, 191-195 (2023).
I. Takagi, T. Kato, Y. Kayanuma, and K. G. Nakamura: Interference of optical phonons in diamond studied using femtosecond pulsed of polarized near-infrared light, Solid State Commun., 350, 11474 (2022).