Single and Poly-crystalline diamond TLS losses study via superconducting LC micro-resonators

Research on diamond has grown rapidly due to its exceptional properties, making it crucial in fields such as quantum technologies and high-power applications like Electron Cyclotron Resonance Heating (ECRH) in nuclear fusion. Accurate measurement of the dielectric loss (tanδ) in diamond is essential, especially for developing ultra-low-loss single-crystal diamond windows for fusion applications. Conventional Fabry-Perot resonators have limited resolution, while superconducting thin-film micro-strip resonators, with Q factors exceeding 106, offer improved sensitivity. We report on loss measurements on single- and polycrystalline diamond samples grown using PECVD, cloning, and HPHT techniques. The results are analyzed using the Two-Level System (TLS) model to assess dielectric losses and material characteristics.