Thursday, September 17 12:45 PM - 2:00 PM
On-Campus Event - — Harney 136
"Twisting Materials: Exploring Nonlinear Optics in Moiré Systems"
Alana Okullo ’22, Howard University, Physics Program Ph.D.
Thursday, September 17, 2026
12:45-2:00pm – HR 136 (coffee hour beginning at 12:15pm)
Since the discovery of topological insulators (TIs), the interplay between topology and symmetry has been a major research topic in condensed matter physics. The emergence of exotic states in a TI depends on the carrier concentration, presence of magnetic atoms, symmetries, chemistry, substrates, spin-orbit coupling, etc. Among different types of exotic quantum states, the discovery of Berry phase effects and nonlinear optical responses, such as shift current, second harmonic generation (SHG), and the photovoltaic Hall effect, brings an excellent opportunity for developing next-generation optoelectronic devices. Recent theoretical and experimental works demonstrated that TIs display a large circular photogalvanic effect (CPGE) and strong SHG effect. Extensive research has been dedicated to realizing and understanding nonlinear optical effects in antiferromagnetic TIs, which are very important for the design of spintronics and topological optoelectronic devices.
In this talk, I will introduce some of the physics behind these exotic states and discuss how we can theoretically study the optical and electronic properties of magnetic topological materials. I will focus on the connections between a material’s structure, symmetry, magnetism, and nonlinear optical response, and how understanding these relationships can help us identify promising materials for future optoelectronic applications.
Alana Okullo graduated from the University of San Francisco with a bachelor’s degree in physics in Spring 2022. Her path into condensed matter physics began in 2021, when she participated in a remote research experience at Howard University under Professor Sugata Chowdhury.
Following her graduation from USF, Alana entered the Physics PhD program at Howard University in Fall 2022 and joined the IBM-HBCU Quantum Center as a fellowship scholar. Still under the guidance of Dr. Chowdhury, her research focuses on the theoretical study of topological and magnetic quantum materials, with particular interest in their nonlinear optical and electronic properties. Her work explores how the underlying interplay of symmetry, topology, and magnetic structure of quantum materials can give rise to under-researched and novel physical phenomena.
Through her doctoral research and the support of the IBM-HBCU Quantum Center, Alana has contributed to published research in quantum materials and has had opportunities to engage with a broad community of physicists, working across quantum science. Namely, studying at Howard has enabled her to give funded talks at APS every year, intern at the Air Force National Laboratory, participate as a visiting student at Harvard in 2024, attend summer school at Los Alamos National Laboratory this summer, and most recently be chosen for the 2026 SCGSR award at the DOE to study at Oak Ridge National Laboratory.
Returning to the University of San Francisco for this colloquium after four years brings Alana back to where her training as a physicist began, now with the opportunity to share the research journey with excitement.
All colloquium talks are open to all members of the USF community.