Control of single charge/spin states using terahertz wave(Fostering Joint International Research)

2018 Fiscal Year Final Research Report

• Project/Area Number: 15KK0215
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Nanostructural physics
• Research Institution: Tohoku Institute of Technology
• Principal Investigator: Shibata Kenji 東北工業大学, 工学部, 准教授 (00436578)
• Research Collaborator: Ensslin Klaus ETH Zurich, Department of Physics, Professor ; Ihn Thomas ; Wegscheider Werner
• Project Period (FY): 2016 – 2018
• Keywords: 量子ドット / テラヘルツ / トランジスタ

Outline of Final Research Achievements

Electrical manipulation and read-out of quantum states in zero-dimensional quantum dots by nanogap metal electrodes is expected to bring about innovation in quantum information processing. In this study, we have investigated a way to control quantum states in nanostructures mainly by terahertz wave. We succeeded in characterizing electronic properties on off-equilibrium states in InAs QDs by terahertz photocurrent spectroscopy. Moreover, an electric-field control of quantized conductance in gold quantum point contacts was demonstrated by adopting a liquid-gated electric-double-layer transistor geometry. Furthermore, we extended our research to some new materials including InSb quantum dots and GaSb quantum wells. These works are opening a way for novel quantum information applications of quantum nanostructure systems.

Free Research Field

ナノエレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

次世代の情報処理として期待される量子情報処理では、単一の光子や電荷、電子スピンなどに情報機能を持たせ、これを外部からの電界や光照射によって制御することで計算を行う。本研究では、電界による単一スピン状態の制御が期待されるInAsやInSb、GaSbなどの化合物半導体ナノ構造を用いたトランジスタを作製し、電子やスピン状態の電界や光による制御に取り組んだ。特に、従来よりも高速な制御が期待されるテラヘルツ光を用いた電子やスピンの制御を可能とするために非常に小さな自己組織化量子ドットを用いた研究を遂行した。