Advanced Photonic and Phononic Interfaces for Diamond Color Centers

Color centers in diamond have emerged as promising solid-state quantum emitters for quantum information processing, serving as stable single-photon sources and spin-based quantum memories. They also provide a versatile platform for quantum network demonstrations, including long-distance entanglement between multiple color centers in diamond. Despite their strong potential for quantum applications, integrating color centers into diamond nanostructures remains technically challenging.

In this talk, Kazuhiro Kuruma will present a novel fabrication approach based on transfer printing of thin-film diamond onto silicon substrates, enabling the realization of fully suspended one- and two-dimensional photonic crystal cavities with quality factors exceeding 1.0 × 10⁵ at visible wavelengths. Using this platform, we have recently demonstrated slow-light photonic crystal waveguides that enhance the spontaneous emission of color centers.

Furthermore, we demonstrate phononic engineering of color centers using one-dimensional phononic crystals exhibiting a complete bandgap around 60 GHz, thereby suppressing spontaneous single-phonon processes that contribute to spin decoherence. These results pave the way toward scalable quantum networks based on diamond nanophotonic and nanophononic platforms.

Subject Matter Level: Intermediate - Assumes basic knowledge of the topic

What You Will Learn:
• What diamond color centers are and why they are useful for quantum technologies.
• How photonic and phononic interfaces can be engineered to control emission and spin properties of diamond color centers.
• How new nanofabrication techniques enable photonic and phononic interfaces in diamond.

Who Should Attend:
• Researchers and engineers in quantum photonics and integrated photonics, especially those interested in color centers and light–matter interactions.
• Scientists working on solid-state quantum systems (e.g., spin qubits, quantum emitters) and scalable quantum technologies.
• Students and researchers interested in nanofabrication, nanophotonics, and emerging quantum devices.

About the Presenter: Kazuhiro Kuruma from The University of Tokyo

Kazuhiro Kuruma is an Assistant Professor at the Research Center for Advanced Science and Technology, The University of Tokyo. He received his Ph.D. in Engineering from The University of Tokyo. Following his doctoral studies, he conducted postdoctoral research at Harvard University as a Postdoctoral Fellow and JSPS Overseas Research Fellow. His research interests include nanophotonics and quantum optics, with particular emphasis on diamond-based quantum devices and spin–phonon interactions. His work has been recognized with several awards, including the Inoue Research Award, the Takayanagi Foundation Research Encouragement Award, and the JSAP Young Scientist Presentation Award.