The development of physics has been along with our understanding of light. The development of quantum mechanics was based on new interpretations of optical phenomena represented by blackbody radiation and photoelectric effect, and recent triumph of detecting the gravitational wave was possible with extremely accurate optical measurements. Not only in the physics, optical science has profound influence on other fields of science and in industries. Our current research in optical science group of Dep. Of Physics includes following interesting topics:

Non-Hermitian (Complex-Index) Nanophotonics

We study Non-Hermitian (NH) Nanophotonics that expands the conventional resonance-based nanophotonics to the conceptually far-reaching open-system domains where various unusual physical effects take place with manifestation of anti-linear symmetry groups, exceptional-point singularities, topological parametric structures, complex energy-spectral chirality, and associated broadband time-asymmetric operations. In this proposed research, we will explore, in both theory and experiments, various strongly-interacting open-system configurations provided by optical gains, losses, scattering, radiative inter-modal coupling, and mixed direct/indirect feedback structures.

Laser Spectroscopy of atom/molecule/ion & Plasma Diagnostics

We are investigating the physical properties and applications of atoms, molecules and ions through laser spectroscopy. We have conducted saturated absorption spectroscopy for cesium atoms and laser cooling studies for trapped calcium ions. Recently, we are focusing on the diagnostics of temperature and density of helium and hydrogen atoms through absorption spectroscopy for helium, hydrogen, and deuterium in plasma states. In addition, the study of analyzing the emission light spectrum from the plasma with the collisional-radiative model is conducting to diagnose the electron temperature and density in the plasma.

Quantum Optics and Quantum Information Sciences

We are working on theoretical and experimental studies of quantum optics and quantum information. Quantum Information Science is nestled at the intersection where information science, nanotechnology, chemistry, computer science, mathematics and physics meet. Rapid experimental developments stimulated by new probing techniques offer many opportunities of working on new problems and impact both theoretical and experimental studies. Our research concerns nonlocality and entanglement for complex systems, quantum plasmonics, quantum machine learning, and quantum biology.

Single Photon Generation and its Applications

We are interested in generation of quantum states of light for their application in nano-, bio- and quantum optical studies. The light-matter interactions at ultimate regime of single photon ? single emitter level is investigated for the next-generation of quantum light source. The single photon source is an essential ingredient in the emerging field of quantum optical applications including quantum information, quantum computation, and quantum metrology which will bring a huge impact on human lives in near future.