Near-field Scanning of Intermodulation Distortion in Superconducting Resonators

Two-dimensional scanning is combined with a method to locally excite intermodulation distortion (IMD) in a cuprate superconducting microwave resonator. The technique provides local maps of second and third order IMD. The two orders originate from distinct processes and require multiple tones in order to both be excited in a narrow passband. This is the first report where multiple orders of IMD are mapped at their points of origin at the operating frequency of the device. Two samples are shown, one pristine sample and one with an engineered defect, revealing a dominance of the defect in the nonlinearity of the device.