Observation of Little-Parks oscillations at temperatures much lower than the critical temperature using a GHz resonator

It is demonstrated that a thin-film Fabry-Perot superconducting resonator can be used to reveal the Little-Parks (LP) effect even at temperatures much lower than the critical temperature. A pair of parallel nanowires is incorporated into the resonator at the point of a supercurrent antinode. As magnetic field is ramped, the Meissner current develops, changing the kinetic inductance of the wires and, correspondingly, the resonance frequency of the resonator, which can be detected. The LP oscillation are revealed as a periodic set of distorted parabolas observed in the transmission of the resonator and corresponding to the states of the wire loop having different vorticities. We also report a direct observation of single and double phase slip events and their statistical analysis.