Magnon-Mediated Qubit Coupling Determined via Dissipation Measurements

Optically addressable spin defects in solids such as nitrogen-vacancy (NV) centers in diamond are promising qubit platforms. A major obstacle to their integration in quantum technologies is the limited on-chip deterministic entanglement pathway. Magnon-mediated interaction mechanisms have attracted significant attention as a solution to this challenge, thanks to the intrinsic NV-magnon magnetic coupling. However, experimental demonstration of the signature of magnon-mediated NV–NV interaction is absent, urging a development of an experimental feedback mechanism to characterize the magnon-mediated coupling strength. Here, we quantify the magnon-mediated coupling of a prototypical weakly interacting system, the NV center with magnons in yttrium iron garnet, by combining qubit dissipation measurements and quantitative theoretical analysis. Our approach is applicable at room temperature, and our general treatment of interactions between two level systems and bosons can be generalized to other relevant quantum transduction platforms. [1]<br/><br/>[1] M. Fukami, et al., PNAS, <b>121</b>, e2313754120 (2024)