Exploiting tunable, ultrastrong nonlinearies of the cavity Cooper-pair transistor system for generating microwave quantum states*

The cavity Cooper-pair transistor (cCPT) device enables the engineering of a wide range of non-linear, effective cavity oscillator interactions through the tunability of both its gate voltage and flux biases. Such nonlinearities can be strong even under low average photon number drives on the cavity. We utilize the recently developed Wigner current vector field (Wigner current) construct to give a geometrical analysis of the formation and possible stabilization of quantum microwave oscillator states in the presence of dissipation and noise for the cCPT.