Universal control of superconducting cavities with weak nonlinearity*

In superconducting cavities, fast universal control usually requires an inherited Kerr nonlinearity on the order of a few kHz. However, in many bosonic quantum error correction codes, such nonlinearities corrupt encoded information, causing errors. Recently, we have engineered an effective quadrature coupling between a cavity and an ancillary qubit based on an arbitrarily weak native dispersive interaction through the use of large phase space displacements. In this talk, we extend the idea of using large displacements in a cavity’s phase space to perform universal control of a superconducting cavity with Kerr nonlinearity on the order of 1 Hz. This control will pave the way toward more sophisticated quantum error correction protocols applied to nearly linear bosonic systems.