Phase noise of a Josephson parametric oscillator

Josephson parametric amplifiers are acquiring a renewed interest in the quantum information community for implementing single-shot readout, and creating entangled photons and squeezed vacuum states. When these parametric amplifiers are driven above an instability threshold, the average number of coherent output photons increases resulting in parametric oscillation. Here we present the results on the experimental study of the phase diffusion properties of such an oscillator by measuring the phase noise spectrum.