Coherent Modulation of Two-Dimensional Moir\'e States with On-Chip THz Waves

TL;DR

This paper demonstrates the coherent modulation of moiré excitons and Mott insulators in 2D TMD bilayers using on-chip THz waves generated by femtosecond laser excitation, enabling dynamic control of layered quantum states.

Contribution

It introduces a method to coherently control moiré states in 2D materials using on-chip THz waves generated by integrated graphene gates, a novel approach for layered quantum device manipulation.

Findings

Successful generation of coherent THz phonon wavepackets from graphene gates.

Precise timing of THz waves modulates moiré excitons and Mott states.

Demonstration of on-chip opto-elastic transduction for 2D material control.

Abstract

Van der Waals (vdW) structures of two-dimensional materials host a broad range of physical phenomena. New opportunities arise if different functional layers may be remotely modulated or coupled in a device structure. Here we demonstrate the in-situ coherent modulation of moir\'e excitons and correlated Mott insulators in transition metal dichalcogenide (TMD) homo- or hetero-bilayers with on-chip terahertz (THz) waves. Using common dual-gated device structures, each consisting of a TMD moir\'e bilayer sandwiched between two few-layer graphene (fl-Gr) gates with hexagonal boron nitride (h-BN) spacers, we launch coherent phonon wavepackets at ~0.4-1 THz from the fl-Gr gates by femtosecond laser excitation. The waves travel through the h-BN spacer, arrive at the TMD bilayer with precise timing, and coherently modulate the moir\'e excitons or the Mott states. These results demonstrate that the fl-Gr gates, often used for electrical control of the material properties, can serve as effective on-chip opto-elastic transducers to generate THz waves for the coherent control and vibrational entanglement of functional layers in commonly used moir\'e devices.