Universal control of a bosonic mode via drive-activated native cubic interactions*

Bosonic modes provide a hardware-efficient alternative to qubit-based quantum information processing. However, achieving universal control on bosons requires access to a nonlinearity, or to resourceful non-Gaussian quantum states like cubic phase states. Superconducting microwave circuits offer such strong nonlinearities but face other challenges, like parasitic state distortion due to the Kerr effect and shorter coherence times.

In this talk, we will demonstrate how these difficulties can be overcome. We harness the 3rd order non-linearity of a SNAIL (Superconducting Nonlinear Asymmetric Inductive eLement) dipole terminated resonator through simultaneous flux and charge pumping to obtain the desired cubic state, 45 times faster than decoherence. In parallel, we minimize the 4th order Kerr effect by adjusting the flux DC bias. Achieving this required meticulous pulse calibration and circuit modeling. We will delve into the details of these processes and discuss how our simulation efforts shed light on the primary causes of infidelity in our current experimental setup.