Generating mechanical and optomechanical entanglement via pulsed interaction and measurement

TL;DR

This paper proposes pulsed interaction schemes in cavity optomechanics to generate and verify optical-mechanical and mechanical-mechanical entanglement outside the resolved-sideband regime, with potential applications in quantum metrology.

Contribution

It introduces two novel schemes for entanglement generation using pulsed optomechanical interactions, including methods to enhance and verify entanglement in realistic experimental conditions.

Findings

Schemes can generate significant entanglement despite optical losses.

Precooling and local squeezing improve entanglement robustness.

Feasibility demonstrated with parameters from recent experiments.

Abstract

Entanglement generation at a macroscopic scale offers an exciting avenue to develop new quantum technologies and study fundamental physics on a tabletop. Cavity quantum optomechanics provides an ideal platform to generate and exploit such phenomena owing to the precision of quantum optics combined with recent experimental advances in optomechanical devices. In this work, we propose schemes operating outside the resolved-sideband regime, to prepare and verify both optical-mechanical and mechanical-mechanical entanglement. Our schemes employ pulsed interactions with a duration much less than the mechanical period and, together with homodyne measurements, can both generate and characterize these types of entanglement. To improve the performance of our schemes, a precooling stage comprising prior pulses can be utilized to increase the amount of entanglement prepared, and local optical squeezers may be used to provide resilience against open-system dynamics. The entanglement generated by our schemes is quantified using the logarithmic negativity and is analysed with respect to the strength of the pulsed optomechanical interactions for realistic experimental scenarios including mechanical decoherence and optical loss. Two separate schemes for mechanical entanglement generation are introduced and compared: one scheme based on an optical interferometric design, and the other comprising sequential optomechanical interactions. The pulsed nature of our protocols provides more direct access to these quantum correlations in the time domain, with applications including quantum metrology and tests of quantum decoherence. By considering a parameter set based on recent experiments, the feasibility to generate significant entanglement with our schemes, even with large optical losses, is demonstrated.