2026 Theses Doctoral

A Time-Domain View of Moiré Quantum Matter

Li, Yiliu

Moiré materials host a rich landscape of exotic quantum phases. A comprehensive understanding of these quantum states relies critically on the experimental techniques used to probe them. Steady-state measurements, including electronic transport and photoluminescence, have advanced rapidly, yet offer only a limited perspective on the mechanisms by which the moiré potential, many-body Coulomb interactions, and electron-phonon coupling cooperate to stabilize emergent phases. Time-domain approaches, by contrast, directly resolve the characteristic timescales of electronic and lattice dynamics, enabling the distinct roles of these degrees of freedom to be disentangled. Furthermore, such techniques are uniquely sensitive to fragile or incipient quantum phases that may remain hidden in equilibrium measurements.

In this dissertation, I investigate the non-equilibrium dynamics of correlated states in moiré superlattices formed from monolayer transition metal dichalcogenides, with particular emphasis on their melting, reordering, and photoinduced formation using time-resolved exciton sensing technique developed in this work. I also examine the multifunctional roles of graphite gates and hexagonal boron nitride layers within the full device architecture, highlighting how these components contribute to the ultrafast dynamics of moiré quantum states and providing additional tuning knobs to control quantum phases.

The last chapter focuses on exciton ordering in moiré heterotrilayer, where the additional layer introduces extra interactions that stabilize new quantum phases. This work demonstrates the advantages of a time-domain perspective for uncovering and understanding moiré quantum matter, and offers an outlook on how ultrafast pump-probe spectroscopy can be used to map the quantum phase landscape of two-dimensional materials.