Alexandra Boltasseva

In this work a hybrid nanoplasmonic‐Weyl Semimetal (WSM) structure is realized for the first time utilizing silver nanopatch antennas and WSM Tantalum Arsenide (TaAs). The studied hybrid WSM‐nanoplasmonic structure demonstrated a substantial, over x4.5 enhancement of the second harmonic generation (SHG) process compared to a bare TaAs film. To realize the hybrid structure while preserving TaAs properties, a scalable, non‐destructive manufacturing approach is developed that involves the fabrication of TaAs flakes from single crystalline TaAs, overgrowth of a silicon nitride overlayer, and drop‐casting of silver nanopatch antennas. The strong polarization response of both the bare flakes, along with the hybrid‐nanoplasmonic cavities demonstrates that this approach uniquely preserves the TaAs crystal structure and its optical response while providing significant enhancement of the nonlinear properties. The developed method allows leveraging the capabilities of plasmonics to control and enhance light‐matter interactions at the nanometer scale to access and engineer WSM response. This work is the first step towards high‐performance nanophotonic devices utilizing WSM topological properties.

A robust process for fabricating intrinsic single‐photon emitters in silicon nitride is recently established. These emitters show promise for quantum applications due to room‐temperature operation and monolithic integration with technologically mature silicon nitride photonics platforms. Here, the fundamental photophysical properties of these emitters are probed through measurements of optical transition wavelengths, linewidths, and photon antibunching as a function of temperature from 4.2 to 300 K. Important insight into the potential for lifetime‐limited linewidths is provided through measurements of inhomogeneous and temperature‐dependent broadening of the zero‐phonon lines. At 4.2 K, spectral diffusion is found to be the main broadening mechanism, while spectroscopy time series reveal zero‐phonon lines with instrument‐limited linewidths.