Noise spectroscopy of a Josephson parametric oscillator

Bistable processes are among the most frequent physical phenomena observed in nature. Josephson parametric oscillators (JPO) based on nonlinear superconducting resonators exhibit bistability where the dynamics of these systems can be qualitatively changed depending on the accessible parameters. When the parametric pump strength of the JPO gradually increases, crossing a threshold, the output field of the JPO settles into oscillating states with a well-defined phase of either 0 or π. In this talk, we present the experimental results on the noise spectroscopy of a JPO using a microwave homodyne interferometric measurement scheme where we characterize the phase and amplitude noise by continuously tracking the oscillator output dynamics. We observe the interstate switching of the oscillating output state between the two stable states of the JPO, which contributes to 1/f² characteristics in the phase noise spectrum and can be suppressed with the increase in the pump strength.