2025/09/05(Fri) 14:00 -15:00 一樓演講廳 1F, Auditorium
Title
Engineering strain superlattices and structured light-matter interaction in 2D semiconducting transition metal dichalcogenides for solid-state quantum simulators and deterministic single photon emitters
Speaker
葉乃裳教授 (Department of Physics, California Institute of Technology) Prof. Nai-Chang Yeh (Department of Physics, California Institute of Technology)Abstract
Semiconducting transition metal dichalcogenides (TMDs) are van der Waals quantum materials with remarkable physical properties that not only provide a platform for exploring fundamental studies of two-dimensional (2D) systems but are also promising for various electronic, photonic, and optoelectronic applications. The reduced dimensionality, direct bandgap, and spin-valley coupling in monolayer (ML) semiconducting TMDs result in strong and dichroic light-matter interaction as well as large exciton binding energies, and the excitonic Rydberg states further offer a solid-state platform to emulate atomic orbital physics. Moreover, the electronic bandstructures and optical properties of ML-TMDs are highly susceptible to strain, yielding reduced bandgaps and enhanced photoluminescence (PL).
In this talk, I’ll describe our recent experimental demonstration and theoretical verification that optical vortex beams carrying orbital angular momentum (OAM) can transfer angular momentum to excitons in ML-TMDs,1,2 which illustrates a mechanism for selective control of exciton orbitals via optical vortices, opening avenues for optically programmable excitonic devices and manipulation of composite quasiparticles in 2D semiconductors. Additionally, using scanning tunneling microscopy / spectroscopy (STM/STS) with light illumination at the tunneling junction to investigate the quasiparticle (QP) dynamics in nanoscale strained ML-TMDs, we find pronounced electronic bandstructure renormalization in the nanoscale strained regions as a function of the photoexcitation wavelength and intensity as well as the strain gradient, implying strong interplay among nanoscale structures, strain, and photoexcited QPs.3 These findings illustrate the feasibility of utilizing nanoscale architectures and structured light with nontrivial spin/orbit angular momentum (SAM/OAM) to manipulate the local electronic bandstructure of ML-TMDs and to enhance the many-body interactions of Rydberg excitons, which is promising for the development of nanoscale energy-adjustable optoelectronic and photonic technologies, including solid-state quantum simulators for interacting excitons and deterministic single photon emitters.
References:
1.Duxing Hao, Chun-I Lu, Ziqi Sun, Siyuan Qiu, Wen-Hao Chang, Akiyoshi Park, Beining Rao, Ting-Hua Lu*, Yann-Wen Lan* and Nai-Chang Yeh*, “Cryogenic scanning photocurrent spectroscopy for materials responses to structured optical fields”, cond-mat/arXiv:2505.24833 (2025).
2.Akiyoshi Park, Iliya Esin, Yinan Chen, Jonas Göser, Rohit Kantipudi, Alexander Högele, and Nai-Chang Yeh*, “Angular momentum transfer between structured light and Rydberg excitons in 2D semiconductors”, preprint (2025).
3.Akiyoshi Park, Rohit Kantipudi, Jonas Göeser, Yinan Chen, Duxing Hao, and Nai-Chang Yeh*, “Strongly enhanced electronic bandstructure renormalization by light in nanoscale strained regions of monolayer MoS2/Au(111) heterostructures”, ACS Nano 18, 29618−29635 (2024).
Poster
Language
演講語言 (Language): in English