Nonlinear Sideband Cooling to a Cat State of Motion

TL;DR

This paper proposes a nonlinear sideband cooling method using bichromatic drives in cavity optomechanics to generate and verify macroscopic quantum superposition states, or cat states, of a mechanical resonator.

Contribution

It introduces a novel protocol leveraging intrinsic nonlinearity and two-phonon dissipation to produce mechanical cat states, even under weak coupling and thermal decoherence.

Findings

Cat states can be generated via nonlinear sideband cooling.

Wigner negativity persists even in weak coupling regimes.

The protocol is robust against thermal decoherence.

Abstract

The ability to prepare a macroscopic mechanical resonator into a quantum superposition state is an outstanding goal of cavity optomechanics. Here, we propose a technique to generate cat states of motion using the intrinsic nonlinearity of a dispersive optomechanical interaction. By applying a bichromatic drive to an optomechanical cavity, our protocol enhances the inherent second-order processes of the system, inducing the requisite two-phonon dissipation. We show that this nonlinear sideband cooling technique can dissipatively engineer a mechanical resonator into a cat state, which we verify using the full Hamiltonian and an adiabatically reduced model. While the fidelity of the cat state is maximized in the single-photon, strong-coupling regime, we demonstrate that Wigner negativity persists even for weak coupling. Finally, we show that our cat state generation protocol is robust to significant thermal decoherence of the mechanical mode, indicating that such a procedure may be feasible for near-term experimental systems.