# Dissipative phonon Fock state production in strong nonlinear optomechanics

## TL;DR

This paper proposes a deterministic method to generate phonon Fock states in nonlinear optomechanical systems using a dissipative protocol, achieving high fidelity even with decoherence, and analyzes its experimental feasibility.

## Contribution

It introduces a novel dissipative protocol for preparing phonon Fock states in nonlinear optomechanics, with robustness and high fidelity demonstrated through numerical simulations.

## Key findings

- Fidelity exceeds 95% in simulations with decoherence.
- Protocol is effective in both good- and bad-cavity regimes.
- Analysis confirms experimental feasibility of the method.

## Abstract

We put forward a deterministic dissipative protocol to prepare phonon Fock states in nonlinear quantum optomechanical devices. The system is composed of a mechanical mode interacting with an optical field via radiation pressure, whereas the light mode is laser-driven in the resolved blue-sideband regime. To keep our results tractable, we have switched to an interaction picture in a displaced basis, where the effective Hamiltonian exhibits the selective photon-phonon interaction explicitly. After proper parameter adjustment and similarly to cavity-cooling schemes, the quantum evolution allows steering the mechanical degree of freedom to the desired Fock state by directing the optical excitations dynamically towards the target phonon state. The numerical results, including decoherence on both the mechanical and the optical degrees of freedom, show to be quite robust in the good- and bad-cavity regimes with fidelities exceeding $95\%$. Lastly, characterization of the achieved nonclassicality, as well as the limitations and feasibility of our protocol under experimental parameters, are also analyzed.