Verification of tristability of nuclear spin polarization in single quantum dot and construction of a unified model including nuclear quadrupole effect

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01745
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 28020:Nanostructural physics-related
• Research Institution: Hokkaido University
• Principal Investigator: ADACHI SATORU 北海道大学, 工学研究院, 教授 (10221722)
• Co-Investigator(Kenkyū-buntansha): 俵 毅彦 日本大学, 工学部, 教授 (40393798) ; 鍜治 怜奈 北海道大学, 工学研究院, 准教授 (40640751) ; 笹倉 弘理 北海道大学, 工学研究院, 准教授 (90374595)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 超微細相互作用 / 核四極子相互作用 / 半導体量子ドット / 電子・核スピン結合系 / 核スピンエンジニアリング

Outline of Final Research Achievements

We have clarified the mechanism of the third stable state of nuclear spin polarization and the anomalous Hanle effect in the longitudinal and transverse magnetic field configurations, respectively, and constructed a model that can predict the dynamics of the electron-nuclear spin coupling system in quantum dots even under arbitrary magnetic field configurations. In particular, we found that the principal axis of the nuclear quadrupole interaction is tilted from the crystal growth direction and has an in-plane component, which is the key to the anomalous Hanle effect. Since the tilt of the principal axis of the nuclear quadrupole interaction can be modulated by applying strain, we fabricated a strain-applied device and confirmed the emission energy level change of quantum dots and the Larmor precession frequency change of bulk AlGaAs by time-resolved Kerr rotation spectroscopy. These results may contribute to the control of nuclear quadrupole effects.

Free Research Field

固体スピン物性

Academic Significance and Societal Importance of the Research Achievements

半導体量子ドットのような多数の原子核スピンに囲まれた１個の局在電子スピンから構成される電子・核スピン結合系では，量子演算，量子メモリ，単一光子源などの研究が精力的に推進されている．しかしこの系では構成する原子が核四極子相互作用を通じて核スピンおよび電子スピンのダイナミクスに影響するが，その詳細は不明であった．我々は独自に発見した核スピン分極の第３安定状態出現と異常ハンル効果を手掛かりに発生機構をそれぞれ特定し，任意の磁場配置での電子・核スピン結合系でのダイナミクスを明らかにするモデルを構築した．これにより電子．核スピン結合系ダイナミクスの予測が可能になり，量子ドットの応用に大きく貢献した．