CAREER: Towards Novel Twist Polaritonics in 2D Crystals and Devices

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

Nontechnical Description: Surface polaritons are a type of hybrid quantum particles resulting from light (photons) strongly coupled to interfacial electric dipoles. These highly confined nano-light waves have emergent properties that do not exist in the separate components alone, giving them the potential to realize novel circuitry for sensing, communications, and information processing.

It is essential to trap light at the nanoscale to generate and manipulate these polaritonic waves. The investigators will image the flow of spatially confined nano-light in a class of engineered two-dimensional (2D) quantum devices with a unique atomic arrangement by stacking and twisting specific 2D layers. This research will uncover the novel characteristics of propagating nano-light waves that occur within these unique structures.

The team expects to harness polaritonic waves to shed light on the fascinating new physics in 2D materials and devices and pave the way for new types of quantum nano-photonic technologies. The PI plans to integrate research with various education and outreach activities to mentor students at the K-12, undergraduate and graduate levels, especially those from underrepresented minority groups.

The team will also participate in integrated outreach programs on 2D materials and nano-optics for the general public offered jointly by Florida State University and the National High Magnetic Field Laboratory. This project is jointly funded by the Electronic and Photonic Materials (EPM) and the Condensed Matter Physics (CMP) programs of the Division of Materials Research (DMR).

Technical Description: The team aims to push the limits of light-matter interactions at unprecedented length scales and employ the emitted polaritonic waves to elucidate and control emergent topological states in two-dimensional (2D) quantum devices. The primary focus is on 2D van der Waals heterostructures and twistronics, a highly tunable topological platform that hosts a full suite of different polaritonic modes (plasmons, phonons, etc.) that can strongly couple with the incident photons far below the diffraction limit.

State-of-the-art scanning near-field optical microscopy techniques will be carried out to directly launch and visualize polaritonic waves as they travel along 2D twisted layers down to the nanometer length scale at the desired long-wavelength photon excitations. In particular, real-space polaritonic nano-imaging grants access to the high photon momentum space that is far beyond what is attainable with conventional far-field optics.

With this unique scanning near-field technique, the project team plans to 1) look for signatures of novel topological polaritonics and investigate their intrinsic characters in 2D quantum devices; 2) explore effective control and manipulation of topological polaritons through the moiré superlattice potential by tuning the relative twist angles and in situ electrical displacement fields; and 3) understand the new physics and exotic quantum phenomena at the infrared/terahertz low energy scales through multi-messenger nano-probe characterizations across multiple dimensions. The research is expected to deepen our understanding of how the topological polaritons can be generated and utilized to probe quantum solids, and harnessing long-lived dissipation-less flow of nano-light for future applications including quantum sensing and communication, topological lasers and quantum circuitry in 2D twisted systems and beyond.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.