# Optimal Control of Hybrid Optomechanical Systems for Generating Non-Classical States of Mechanical Motion

## TL;DR

This paper demonstrates how coupling a two-level system to a cavity optomechanical system and applying optimal control techniques can generate non-classical states of mechanical motion with negative Wigner function regions.

## Contribution

It introduces a hybrid optomechanical system with a two-level system and develops optimal control methods to produce non-classical mechanical states beyond linear regimes.

## Key findings

- Successfully drives the system to non-classical target states
- Uses realistic experimental parameters for optimization
- Naive control schemes are ineffective for non-classical state preparation

## Abstract

Cavity optomechanical systems are one of the leading experimental platforms for controlling mechanical motion in the quantum regime. We exemplify that the control over cavity optomechanical systems greatly increases by coupling the cavity also to a two-level system, thereby creating a hybrid optomechanical system. If the two-level system can be driven largely independently of the cavity, we show that the non-linearity thus introduced enables us to steer the extended system to non-classical target states of the mechanical oscillator with Wigner functions exhibiting significant negative regions. We illustrate how to use optimal control techniques beyond the linear regime to drive the hybrid system from the near ground state into a Fock target state of the mechanical oscillator. We base our numerical optimization on realistic experimental parameters for exemplifying how optimal control enables the preparation of decidedly non-classical target states, where naive control schemes fail. Our results thus pave the way for applying the toolbox of optimal control in hybrid optomechanical systems for generating non-classical mechanical states.