Quantum-state steering in optomechanical devices

TL;DR

This paper demonstrates that optomechanical systems can exhibit quantum-state steering, allowing the quantum state of a mechanical oscillator to be controlled via measurements on the optical field, under realistic conditions.

Contribution

It shows that optomechanical devices can realize EPR-type entanglement and quantum-state steering with feasible detection efficiencies, linking steerability to sub-Heisenberg state tomography.

Findings

Steering is achievable with as low as 50% detection efficiency.

Steerability conditions match those for sub-Heisenberg state tomography.

Quantum entanglement between light and mechanics demonstrated in the quantum regime.

Abstract

We show that optomechanical systems in the quantum regime can be used to demonstrate EPR-type quantum entanglement between the optical field and the mechanical oscillator, via quantum-state steering. Namely, the conditional quantum state of the mechanical oscillator can be steered into different quantum states depending the choice made on which quadrature of the out-going field is to be measured via homodyne detection. More specifically, if quantum radiation pressure force dominates over thermal force, the oscillator's quantum state is steerable with a photodetection efficiency as low as 50%, approaching the ideal limit shown by Wiseman and Gambetta [Phys. Rev. Lett. {\bf 108}, 220402 (2012)]. We also show that requirement for steerability is the same as those for achieving sub-Heisenberg state tomography using the same experimental setup.