Ultrafast Floquet engineering of Fermi-polaron resonances in charge-tunable monolayer WSe devices.

Fermi polarons are emerging quasiparticles when a bosonic impurity immersed in a fermionic bath. Depending on the boson-fermion interaction strength, the Fermi-polaron resonances exhibit either attractive or repulsive interactions, which impose further experimental challenges on understanding the subtle light-driven dynamics. Here, we report the light-driven dynamics of attractive and repulsive Fermi polarons in monolayer WSe devices.

Ultrafast non-excitonic valley Hall effect in MoS/WTe heterobilayers.

The valley Hall effect (VHE) in two-dimensional (2D) van der Waals (vdW) crystals is a promising approach to study the valley pseudospin. Most experiments so far have used bound electron-hole pairs (excitons) through local photoexcitation. However, the valley depolarization of such excitons is fast, so that several challenges remain to be resolved.