Terahertz spectroscopy of van der Waals heterostructures

Van der Waals (vdW) heterostructures have emerged as a captivating platform for investigating quantum phases of matter. An intriguing and important direction is the exploration of novel low-energy electrodynamics and light-matter interactions in these systems, a pursuit hindered by subwavelength sample sizes.

We directly address this challenge through on-chip THz spectroscopy, a technique that enables broadband, time-resolved THz measurements in micron-sized, atomically thin vdW heterostructures. Building on this technique, we pursue three interconnected thrusts:

• Probing the low-energy electrodynamics of correlated and topological quantum phases in moiré superlattices.

• Combining optical drive with THz readout to explore and control transient quantum states.

• Exploiting the unique energy and length scales of moiré superlattices to access strongly driven regimes of light-matter interaction.

ARPES-informed engineering of 2D quantum materials

Angle-resolved photoemission spectroscopy (ARPES), a direct probe of electronic structure, offers rich microscopic insights into the behavior of correlated electrons. A rapidly advancing frontier is the integration of ARPES with tunable 2D materials, an approach poised to address fundamental questions in condensed matter physics and guide the design of novel quantum materials.

Leveraging our expertise in high-precision ARPES experiments, nanofabrication of 2D material devices, and long-standing collaborations with world-leading synchrotron facilities, we explore the following research directions:

• Utilizing spontaneous charge transfer and displacement fields in vdW heterostructures to explore correlated phases free from dopant-induced disorder and with tunable microscopic interactions.

• Combining materials with distinct order parameters at pristine vdW interfaces to engineer novel quantum states.

• Exploiting uniaxial strain as a tuning knob in ARPES to control the band structures and electronic phases of 2D materials.