Coherent Modulation\nof Two-Dimensional Moire\nStates with On-Chip THz Waves

van der Waals (vdW) structures host a broad range of\nphysical phenomena.\nNew opportunities arise if different functional layers are remotely\nmodulated or coupled in a device structure. Here we demonstrate the\nin situ coherent modulation of moiré excitons and correlated\nMott insulators in transition metal dichalcogenide (TMD) moirés\nwith on-chip terahertz (THz) waves. Using common dual-gated device\nstructures of a TMD moiré bilayer sandwiched between two few-layer\ngraphene (fl-Gr) gates with hexagonal boron nitride (h-BN) spacers,\nwe launch coherent phonon wavepackets at ∼0.4–1 THz\nfrom the fl-Gr gates by femtosecond laser excitation. The waves travel\nthrough the h-BN spacer, arrive at the TMD bilayer with precise timing,\nand coherently modulate the moiré excitons or Mott states.\nThese results demonstrate that the fl-Gr gates, often used for electrical\ncontrol, can serve as on-chip opto-elastic transducers to generate\nTHz waves for coherent control and vibrational entanglement of functional\nlayers in moiré devices.