Description
Van der Waals (vdW) heterostructures exhibit a wide range of exotic many-body quantum phenomena that can be tuned in situ using electrostatic gates. Understanding the conditions under which these phenomena emerge and finding ways to engineer them, is of great fundamental interest and important for deterministically designing materials for new applications. In this talk, I will discuss how vdW heterostructures form sub-wavelength cavities in the THz frequency range due to their micron-size, confining low-energy light into the near field. I will introduce time-domain on-chip THz spectroscopy as a technique to capture the cavity electrodynamics, probing the response of 2D materials to light on their natural frequency (~THz/meV) scales. This technique overcomes the mismatch between free-space THz wavelengths (~300 um) and sample size (~10 um) by measuring the optical conductivity on-chip, in the near field, and at finite momenta. I will illustrate how the properties of gate-tunable vdW heterostructures can be modified and controlled due to cavity effects.
