A non-equilibrium perspective of moiré quantum matter

by Dr Yiping Wang (Columbia University)

Wednesday 13 Aug 2025, 10:30 → 11:30 Asia/Shanghai

Tencent Meeting link: https://meeting.tencent.com/dm/ANRJ6FraVIJT 

Meeting ID:665961178, no password

 

Abstract:

Over decades, the search for and understanding emergent quantum phases has posed significant challenges for physicists. Moiré systems, with their tunable superlattices, provide a powerful platform to investigate quantum phases, such as correlated insulators, superconductivity, magnetism and beyond. Particularly, twisted MoTe₂ bilayers have recently revealed exotic fractional quantum anomalous Hall (FQAH) and fractional topological insulators (FTI), which have never been observed in conventional quantum materials. In this talk, I will introduce a nonequilibrium approach to detect equilibrium state. Using transient optical spectroscopy, we uncovered nearly 20 hidden states at fractional fillings in twisted MoTe₂ system that remain undetected in static measurements. This approach provides extreme sensitivity and direct access to the relevant timescales that govern the motion of electronic and phononic degrees of freedom, enabling their underlying roles to be directly revealed. Specifically, I will highlight how critical electron hopping pathways within the moiré potential contribute to the stabilization of correlated phases. Ultimately, these findings not only expose hidden states but also emphasize the dynamic nature of topological protection, motivating further experimental and theoretical exploration of exotic quantum phases.

 

Biography:

Yiping Wang is currently a postdoctoral researcher and Max Planck New York center fellow at Columbia University where she has been working with Prof. Xiaoyang Zhu and James Hone. Her work focuses on light-matter interactions in quantum materials, with an emphasis on pioneering transient studies of quantum phases in moiré systems. Yiping obtained her bachelor’s degree in physics from Renmin University of China in 2016, where she conducted research with Prof. Shancai Wang and Liyuan Zhang on nano device fabrication and transport. She then pursued graduate studies at Boston College, where she received her Ph.D. in 2022 under the supervision of Prof. Ken Burch. Her doctoral research focused on exploring collective modes and charge transfer in heterostructures via Raman spectroscopy. For this work, she was honored with the American Physical Society’s Best Dissertation in Magnetism Award.