Quasi-fluxon bubble dynamics in a rapid oscillatory microwave field

In this article, we numerically study the dynamics of a two-dimensional quasi-fluxon bubble in an oscillatory regime stabilized by a localized annular force under a rapidly oscillating microwave field. The bubble exhibits two distinctly dynamical regimes. At first, the oscillation of the bubble wall scales up linearly with the microwave field frequency until it reaches a cutoff, after which it detaches from the external field, returning to its natural oscillation frequency. The amplitude of the quasi-fluxon oscillations is inversely proportional to the square of the microwave field frequency. Following a simplified model based on the Kapitza approach, we proved that this dynamical behavior is characteristic of systems with a harmonic potential subjected to a rapidly oscillating field. Possible applications of microwave detection are discussed.