Optomechanical state reconstruction and nonclassicality verification beyond the resolved-sideband regime

TL;DR

This paper introduces a new method for reconstructing and verifying the quantum state of mechanical resonators in optomechanics without needing high-quality cavities, enabling broader experimental access to nonclassical states.

Contribution

The authors develop a tomographic technique that exploits the full optomechanical Hamiltonian to read out mechanical states via optical pulses, bypassing the need for high-Q cavities and full state transfer assumptions.

Findings

Enables quantum state reconstruction without high-Q optical cavities.

Allows witnessing nonclassical features with minimal measurements.

Facilitates verification of mechanical quantum states in diverse systems.

Abstract

Quantum optomechanics uses optical means to generate and manipulate quantum states of motion of mechanical resonators. This provides an intriguing platform for the study of fundamental physics and the development of novel quantum devices. Yet, the challenge of reconstructing and verifying the quantum state of mechanical systems has remained a major roadblock in the field. Here, we present a novel approach that allows for tomographic reconstruction of the quantum state of a mechanical system without the need for extremely high quality optical cavities. We show that, without relying on the usual state transfer presumption between light an mechanics, the full optomechanical Hamiltonian can be exploited to imprint mechanical tomograms on a strong optical coherent pulse, which can then be read out using well-established techniques. Furthermore, with only a small number of measurements, our method can be used to witness nonclassical features of mechanical systems without requiring full tomography. By relaxing the experimental requirements, our technique thus opens a feasible route towards verifying the quantum state of mechanical resonators and their nonclassical behaviour in a wide range of optomechanical systems.