Ultrafast quantum path interferometry for optical excitation path selection

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22141
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 30:Applied physics and engineering and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Nakamura Kazutaka 東京工業大学, 科学技術創成研究院, 准教授 (20302979)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 量子経路干渉 / フェムト秒 / 量子コヒーレンス / コヒーレントフォノン

Outline of Final Research Achievements

We developed an ultrafast quantum path interferometry to measure the interference of multiple quantum mechanical paths during optical excitation in materials using femtosecond pulses with controlled relative phase and polarization. While both electronic and phonon interferences were observed in parallel polarization pule pair irradiation on GaAs, only phonon interferences were observed in orthogonal polarization pulse pair irradiation. We developed a theoretical model of quantum path interference with the polarization dependence of electron-phonon interactions and reproduced the experimental results in quantum path interference in the induced Raman process. In exciton quantum beats in GaAs/AlGaAs quantum wells, interference patterns corresponding to path interference in the optical absorption process were obtained.

Free Research Field

量子光物性物理

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した超高速量子経路干渉計法により，光励起過程の終状態の解析だけでは知ることのできない凝縮系物質内の光遷移過程中の量子経路を，干渉縞のパターンから選別することができた。量子経路干渉の様子の計測は，現象を量子力学的な立場から理解する上で必要不可欠である。これにより，支配的な経路の同定やどの経路の干渉が量子力学特有の現象を引き起こしているのかの情報を与えるものである。この方法は，量子経路まで含めた新しい物質科学への応用が期待される技術である。