Optical-force-mediated coupling between levitated nanospheres can go ultrastrong

TL;DR

This paper theoretically demonstrates that optical-force-mediated interactions between two levitated nanospheres can achieve ultrastrong coupling, revealing potential for entanglement and quantum state manipulation in optomechanical systems.

Contribution

It introduces a new regime of ultrastrong coupling mediated by optical forces between nanospheres, with experimentally accessible signatures for quantum entanglement detection.

Findings

Ultrastrong coupling regime achievable via optical-force mediation.

Entanglement signatures detectable through position/momentum correlations.

Dynamical Casimir effect observable with fast tweezer modulation.

Abstract

We theoretically investigate the effect of optical-force-mediated interactions onto the quantum dynamics of a pair of dielectric nanospheres optically trapped in two neighboring optical tweezers. Thanks to the interference between the tweezer beams and the elastically scattered light by the other nanosphere, the effective inter nanosphere coupling can reach the ultrastrong coupling regime. Experimentally accessible signatures of the entangled nature of the quantum ground state are highlighted, including entanglement witnesses based on position/momentum correlation functions and a sizable dynamical Casimir excitation upon a fast modulation of the tweezer's properties.