Fast and robust cat state preparation utilizing higher order nonlinearities

TL;DR

This paper introduces a method to generate Schrödinger cat states more quickly by tuning higher order nonlinearities, and proposes a practical implementation using Rydberg atoms with optimal control techniques.

Contribution

It demonstrates how multiple higher order nonlinear interactions can reduce cat state preparation time and suggests a feasible experimental platform with Rydberg atoms.

Findings

Shorter cat state preparation times achieved with higher order nonlinearities

Optimal control scheme enables starting from vacuum state

Proposed Rydberg atom ensemble as a practical platform

Abstract

Cat states are a valuable resource for quantum metrology applications, promising to enable sensitivity down to the Heisenberg limit. Moreover, Schr\"odinger 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. A pathway to realize cat states is via utilizing single Kerr-type anharmonicities as found in superconducting devices as well as in Rydberg atoms. Such platforms nevertheless utilize only the second order anharmonicity, which limits the time it takes for a cat state to be prepared. Here we show how proper tuning of multiple higher order nonlinear interactions leads to shorter cat state preparation time. We also discuss practical aspects including an optimal control scheme which allows us to start the state preparation from the vacuum state under standard single mode driving. Lastly, we propose an ensemble of Rydberg atoms that exhibits higher order nonlinearities as a platform to prepare cat states in the laboratory.