Vacuum squeezing in resonant SNAIL parametric amplifier operated near the Kerr-free point

Squeezed states are an important resource in certain quantum measurements and computing architectures. Single-mode squeezed states of traveling microwave photons are commonly created by quantum-limited parametric amplifiers operated in phase-sensitive mode. One major impediment to creating a highly squeezed state is the distortion of the state at high gain due to Kerr (fourth-order) nonlinearity, which is innate to most Josephson junction-based parametric amplifiers. One exception is the SNAIL parametric amplifier (SPA), which can be designed and flux-biased to reach a point where the Kerr nonlinearity reaches zero and third-order nonlinearity is still significant. We will report on vacuum squeezing experiments using a resonant three-wave-mixing SPA operated in the vicinity of its Kerr-free point, from which we infer a level of vacuum squeezing greater in magnitude than -4dB at the plane of the SPA. We will further discuss the techniques used to calibrate the measurement setup, and correlate squeezing performance with measurements of amplifier intermodulation distortion.