Hybrid quantum systems combine complementary physical platforms to access regimes beyond the capabilities of a single system. A rapidly emerging class of such systems employs cryogenic solids as host materials, where impurities are embedded within or positioned atop thin cryocrystal films and coupled to superconducting microwave circuits. These systems are particularly attractive for quantum memories, as cryogenic solids provide soft, magnetically quiet environments that preserve coherence. However, intrinsic loss mechanisms in superconducting circuits limit performance, and understanding how cryogenic solids interact with superconducting materials has become a critical bottleneck. Recent observations of reduced quasiparticle losses in granular aluminum resonators covered by parahydrogen cryocrystals highlight the potential of cryocrystals to modify loss processes, while leaving open whether these effects are general or material-specific. Addressing this question is essential to advancing cryocrystal hybrid quantum systems.

This project aims to systematically study and quantify losses in hybrid quantum systems composed of cryocrystals and superconducting circuits and addresses the hypothesis that cryocrystals can be used to modify and mitigate loss mechanisms in superconducting circuits. The main objectives are to identify optimal combinations of cryocrystal and superconducting materials, to disentangle dielectric and quasiparticle losses in hybrid architectures, and to determine how cryocrystals influence quasiparticle generation and relaxation following ionizing radiation and optical excitation.