Abstract: Today’s optical devices are getting smaller and smaller to realize new functionalities and reduce energy consumption. However, miniaturization becomes more difficult when the size falls below wavelength because of the lack of deep sub-wavelength electromagnetic resonance, an enabling effect for a wide range of applications, from radio-frequency communication to silicon photonics, metamaterials, and metasurfaces.

Quantum electronic transition has the potential to become a new platform to continue the miniaturization of optical devices. An electronic transition can resonantly absorb, scatter, and convert photon energy. It has the same scattering matrix as that of classical optical resonators in the single-photon regime. Moreover, it has many advantages over classical resonators: it is extremely compact; is easily tunable by laser, magnetic, or electric fields; and can be highly nonlinear.

In this talk, I will start by showing an intriguing function realized by extremely compact resonance. Then, I will discuss how electronic transitions could be used to realize classical functions such as antennas and metasurfaces. Then, I will discuss how electronic transition could rewrite some of the fundamental electromagnetic scattering law when combined with nontrivial topological charge found at Weyl points.

Bio: Zongfu Yu is the Dugald C. Jackson Assistant Professor in the department of electrical and computer engineering at the University of Wisconsin-Madison. His research interests include computational electromagnetics, optics, machine vision, and sensing. He received his Ph.D. in applied physics and M.S. in management science and engineering, both from Stanford University, and a B.S. degree in physics from the University of Science and Technology of China.