Physical oscillations having different dissipation rates couple to create non-Hermitian singularities called exceptional points (EPs) where two or more eigenstates coalesce into one and the system’s Hamiltonian is non-diagonalizable and non-normalizable. Utilizing EPs and related topological properties, physical waves can be manipulated in various ways including control of propagation direction and enhancement of resonance. 

Our research on non-Hermitian physics ranges from theoretical backgrounds to associated device applications.

EPs and related intriguing phenomena are studied using simplified Hamiltonian formalism and LRC circuit experiments in depth.
The theoretical developments are intensively exploited to design innovative photonic devices such as on-chip optical isolators, ultra-broadband optical couplers, and high-speed optical modulators.