Low-Dimensional Quantum Device Research Unit

Principal Investigator

PI Name

Yuya Shimazaki

Title

Unit Leader

Brief Resume

2016	Ph. D., The University of Tokyo
2016	Postdoctoral Researcher, The University of Tokyo
2017	Postdoctoral Researcher, Quantum Photonics Group, ETH Zurich, Switzerland
2021	Research Scientist, Quantum Electron Device Research Team, RIKEN Center for Emergent Matter Science
2024	Project Associate Professor, Quantum-Phase Electronics Center, School of Engineering, The University of Tokyo (-present)
2024	Unit Leader, Low-Dimensional Quantum Device Research Unit, Cross-Divisional Materials Research Program, RIKEN CEMS (-present)

Outline

Our group focuses on the exploration of physics in novel quantum devices utilizing low-dimensional structures formed by the moiré interference effects of crystal lattices and semiconductor microfabrication, primarily based on two-dimensional materials. In particular, we aim to elucidate the quantum many-body physics and quantum device physics in semiconductor moiré superlattices through electrical control and probing and control through optical excitation. Starting from bulk single crystals of layered compounds, our research comprehensively covers the fabrication of heterostructures of two-dimensional materials, device fabrication, electrical control, optical measurements, and electrical transport measurements at extremely low temperatures, as well as the development of necessary equipment and software.

Research Fields

Physics, Engineering, Materials Sciences

Keywords

Two-dimensional materials (2D materials)
Nanodevices
Spectroscopy
Strongly correlated system
Condensed matter physics

Results

Electrical control and excitonic sensing of semiconductor moiré lattices

Two-dimensional materials, which are atomically thin materials, can acquire new functionalities by being stacked together. When two-dimensional material crystals with similar lattice constants are overlaid, moiré interference can create periodic nanostructures with a period of about 10 nanometers, longer than the original crystal’s periodicity. By utilizing transition metal dichalcogenides, which are semiconductor two-dimensional materials, it is possible to electrically control and optically detect electrons in these moiré lattices. By fabricating high-quality heterostructures, we have successfully realized insulating states arising from strong electron correlations in such electrically controlled semiconductor moiré lattices. Specifically, using excitonic transitions as sensors, we have succeeded in optically detecting unique interlayer charge transfer behaviors and the formation of charge order. Additionally, we have established various control methods, such as the electrical control and optical detection of tunnel coupled states of holes in the moiré lattice, the electrical control of hybrid states of excitons, and the Feshbach resonance through electrical manipulation. Such highly controllable semiconductor moiré lattices hold great potential for use as simulators of quantum condensed matter physics.

(a) A superlattice created by moire interference of two-dimensional material crystals (moire lattice) (b) Strongly correlated electrons in a semiconductor moire superlattice and sensing by excitons (c) Electrical control of hybrid states of excitons (d) Feshbach resonance of excitons and holes induced by electrical control

Members

Yuya Shimazaki	Unit Leader	yuya.shimazaki[at]riken.jp

Publications

A. Popert, Y. Shimazaki, M. Kroner, K. Watanabe, T. Taniguchi, A. Imamoglu, and T. Smolenski

Optical Sensing of Fractional Quantum Hall Effect in Graphene

Nano Lett. 22, 7363–7369 (2022)
I. Schwartz, Y. Shimazaki, C. Kuhlenkamp, K. Watanabe, T. Taniguchi, M. Kroner, and A. Imamoglu

Electrically tunable Feshbach resonances in twisted bilayer semiconductors

Science 374, 336 (2021)
T. Smoleński, P. E. Dolgirev, C. Kuhlenkamp, A. Popert, Y. Shimazaki, P. Back, X. Lu, M. Kroner, K. Watanabe, T. Taniguchi, I. Esterlis, E. Demler and A. Imamoğlu

Signatures of Wigner crystal of electrons in a monolayer semiconductor

Nature 595, 53 (2021)
Y. Shimazaki, C. Kuhlenkamp, I. Schwartz, T. Smolenski, K. Watanabe, T. Taniguchi, M. Kroner, R. Schmidt, M. Knap, and A. Imamoglu

Optical Signatures of Periodic Charge Distribution in a Mott-like Correlated Insulator State

Phys. Rev. X 11, 021027 (2021)
Y. Shimazaki, I. Schwartz, K. Watanabe, T. Taniguchi, M. Kroner and A. Imamoglu

Strongly correlated electrons and hybrid excitons in a moiré heterostructure

Nature 580, 472 (2020)
Y. Shimazaki, M. Yamamoto, I. V. Borzenets, K. Watanabe, T. Taniguchi, and S. Tarucha

Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene

Nat. Phys. 11, 1032 (2015)