On Monday, May 11, Keio University hosted the eleventh installment of the OIST-Keio Showcase Talk Series, titled “Resonance Matters - Micro-Optical Resonators for Quantum, Bio, and Energy Applications,” together with its J-PEAKS partner university, Okinawa Institute of Science and Technology (OIST). The collaborative workshop brought together researchers from OIST’s Light-Matter Interactions for Quantum Technologies Unit and the Tanabe Photonic Structure Laboratory in the Department of Electronics and Electrical Engineering, Faculty of Science and Technology at Keio University, for a full day of discussions focused on the latest advances in micro-optical resonators, particularly their applications in quantum technologies and energy-related photonics.
In opening remarks to kick off the workshop, Professor Síle Nic Chormaic from the OIST emphasized the significance of collaboration between OIST and Keio University made possible by the framework of the J-PEAKS initiative. She expressed expectations for further deepening collaborative research utilizing micro-optical resonators in order to advance light–matter interaction research that supports quantum technologies and to strengthen the research capabilities of both institutions.
The morning began with a presentation by Keio University Professor Takasumi Tanabe, who spoke about cutting-edge research on microresonator frequency combs for THz transmission and signal processing. At the Tanabe Photonic Structure Laboratory, researchers are working to create ultra-energy-efficient photonic integrated circuits through the use of optical technologies for signal processing. By leveraging nanofabrication technologies to maximize light–matter interactions, the laboratory aims to develop optical switches operable with extremely small amounts of energy, optical buffers capable of freely controlling the speed of light, and photonic quantum information processing devices.
Professor Yasutomo Ota of the Department of Applied Physics and Physico-Informatics at Keio University conducts research across a broad range of fields, including quantum photonic integrated circuits, magnetic nanophotonics, semiconductor optical twistronics, and topological nanophotonics. In his workshop session, Professor Ota presented his findings on hybrid integrated quantum photonics enabled by transfer-printing technology. His laboratory investigates versatile technologies for heterogeneous material integration based on semiconductor nanophotonic structures and transfer-printing methods. The ability to freely combine diverse materials into nanophotonic structures could pave the way for a wide range of next-generation optical technologies.
Assistant Professor Shun Fujii from the Department of Physics at Keio University presented research on imaging phenomena induced by dynamic strain in two-dimensional materials. His work focuses on maximizing nonlinear light–matter interactions in microscopic regions, with the goal of uncovering novel physical properties and advancing applications in quantum optoelectronics. The presentation introduced nonlinear optical devices combining ultrahigh-Q silica microcavities with two-dimensional materials, highlighting cutting-edge developments in nanophotonics research.
From OIST, Staff Scientist Christophe Pin introduced research utilizing whispering-gallery-mode (WGM) resonators at OIST. WGM resonators provide exceptional optical confinement and high Q factors, enabling strong light–matter interactions, nonlinear optical processes, and highly sensitive transduction mechanisms. These characteristics make WGM resonators promising platforms not only for emerging quantum systems but also for applications in sensing, frequency conversion, and photonic energy management in energy-related fields.
Mohammed Zia Jalaludeen, a Ph.D. candidate at OIST, presented research in cavity quantum electrodynamics (QED) aimed at realizing strong interactions between light and quantum states by combining nitrogen-vacancy (NV) centers in diamond with thin-walled WGM microresonators. Through the use of WGM resonators, the research seeks to achieve quantum control at the single-photon level and highly efficient photon conversion.
Assistant Professor Hiroki Takahashi from the Experimental Quantum Information Physics Unit presented research on the integration of optical microcavities into monolithic linear ion traps for quantum photonic interconnects. His unit conducts research on highly controllable quantum systems, with a particular focus on developing ion traps incorporating optical interfaces based on single photons. By trapping single atomic ions within high-Q micro-optical resonators, strong coupling between ions and photons can be achieved. Assistant Professor Takahashi explained that his research aims both to explore novel physics in such strongly coupled systems and to develop functional quantum devices utilizing ion–photon coupling for networked quantum information processing.
During the lunch break, students from OIST and Keio University presented posters, providing a space conducive for faculty, staff, and students from both institutions to interact and network. Following the workshop, participants were taken on a laboratory tour of OIST’s Light–Matter Interactions for Quantum Technologies Unit, where Keio faculty members and students learned more about its cutting-edge research environment and facilities.
On the day following the workshop, liaison officers and university research administrators from both institutions convened the OIST-Keio Strategic Liaison Meeting to exchange views on strengthening future collaboration. Through the robust partnership fostered by the J-PEAKS initiative, OIST and Keio University will continue working together to elevate Japan’s research capabilities.