Suppression of low-frequency charge noise in superconducting resonators by surface spin desorption

Noise and decoherence due to spurious two-level systems located at material interfaces are long-standing issues for solid-state quantum devices. Efforts to mitigate the effects of two-level systems have been hampered by a lack of knowledge about their chemical and physical nature. Here, by combining dielectric loss, frequency noise and on-chip electron spin resonance measurements in superconducting resonators, we demonstrate that desorption of surface spins is accompanied by an almost tenfold reduction in the charge-induced frequency noise in the resonators. These measurements provide experimental evidence that simultaneously reveals the chemical signatures of adsorbed magnetic moments and highlights their role in generating charge noise in solid-state quantum devices. The performance of solid-state quantum devices is often affected by low-frequency noise that appears to arise from the presence of two-level defects. Here the authors show that surface spins that cause magnetic noise are an origin of dielectric noise in superconducting resonators.