Designing a photonic structure that exhibits targeted optical properties is very challenging. Like material compositions, geometrical configurations, length scales, etc., the number of parameters is numerous, and the designing space is vast. We leverage a novel approach based on quantum-mechanical bits (i.e., qubits), where a single qubit is of a two-level system like a bit but with a continuous phase. With those qubits, we can map the design process of the photonic structure onto a quantum-entangled-objective optimization problem. We will exploit quantum computing platforms like IBM Quantum, IonQ, or D-wave. They can find an optimal state of photonic structure at a given objective function with a time scale several order-of-magnitude faster than a classical computer. In upcoming years, our lab will build the engineering bridge that connects the designing process of the photonic structure and the manipulation of qubits on quantum computers, yielding a highly efficient photonic solver.

Guided high-speed nanoswimmer can play essential roles in many applications like targeted- drug delivery, in-situ diagnoses, and nanofabrication. Nanoswimmer in this context describes an artificial nanoscale object in liquid that either relies on external energy sources (e.g., light, heat, or sound wave) to move or has an on-board propulsion mechanism to perform a specific task. We recently observed that extremely fast (> 100,000 μm/s, ~10⁶ body-length/s) ballistic Au NP swimmers could be directed by near-infrared light as an external energy source. We assume that the light exerts radiative pressure (so-called “optical force”) on the plasmonic nanoswimmer. At the same time, the nanoswimmer excited by the light at the SPR peak can generate a nanoscale bubble to encapsulate itself (i.e., supercavitation) to create a virtually frictionless environment for it to move at a very high speed. However, the current theoretical or experimental works have not been sufficient to elucidate the physics. In the upcoming few years, our group will study the fundamental physics of these findings.

The light-matter interaction has received excellent research attention, as the coherent wave nature of photons at the nanoscale enables the systematic engineering of optical properties in interfacial nanostructures. The light-field distribution, radiation, and dissipation can be tuned to achieve extraordinary optical phenomena, such as optical trapping, surface plasmon, and meta-materials. Still, there is an enormous unexplored space of light-matter interactions at the nanoscale. For example, it becomes challenging to explore these areas when photonics in nanostructures is coupled with the dynamics of multiphase thermofluids, which are usually far out of equilibrium. Also, optoelectronic devices like photovoltaics or light-emitting diodes can leverage novel nanostructures to improve energy conversion efficiencies by enhancing photon absorption or emission rate. Our group explores light-matter interactions and couples them with photonic applications.