Fast and robust cat state preparation utilizing higher order nonlinearities

Cat states are a valuable resource for quantum metrology applications, promising to enable sensitivity down to the Heisenberg limit. Moreover, Schrödinger cat states, based on a coherent superposition of coherent states, show robustness against phase-flip errors making them a promising candidate for bosonic quantum codes. Despite its applications, cat states are difficult to generate. A coherent state can evolve into a cat state under a single Kerr-type anharmonicity as found in superconducting devices as well as Rydberg atoms. Such platforms nevertheless exhibit only the second order anharmonicity, which limits the time it takes for a cat state to be prepared. In this talk, we will show how proper tuning of higher order nonlinearities leads to shorter cat preparation time. We will also discuss practical aspects including optimal control schemes and ways to mitigate decoherence. Lastly, we propose an ensemble of Rydberg atoms that exhibits higher order nonlinearities as a platform to prepare cat states in the laboratory.