Quantum-correlated motion and heralded entanglement of distant optomechanically coupled objects

TL;DR

This paper demonstrates how quantum fluctuations in a two-mode optical cavity can induce entanglement and non-classical correlations between distant optomechanical objects, with potential for heralded entanglement via photon detection.

Contribution

It reveals that quantum fluctuations can generate entanglement between distant mechanical oscillators in a ring cavity, a novel insight into dissipation-induced quantum correlations.

Findings

Quantum fluctuations induce positive correlations in particle motion.

Detection of scattered photons enables heralded entanglement.

Entanglement correlates with squeezing of relative motion.

Abstract

The motion of two distant trapped particles or mechanical oscillators can be strongly coupled by light modes in a high finesse optical resonator. In a two mode ring cavity geometry, trapping, cooling and coupling is implemented by the same modes. While the cosine mode provides for trapping, the sine mode facilitates ground state cooling and mediates non-local interactions. For classical point particles the centre-of-mass mode is strongly damped and the individual momenta get anti-correlated. Surprisingly, quantum fluctuations induce the opposite effect of positively-correlated particle motion, which close to zero temperature generates entanglement. The non-classical correlations and entanglement are dissipation-induced and particularly strong after detection of a scattered photon in the sine mode. This allows for heralded entanglement by post-selection. Entanglement is concurrent with squeezing of the particle distance and relative momenta, while the centre-of-mass observables acquire larger uncertainties.