Dynamics of levitated nanospheres: towards the strong coupling regime

Understand

The use of levitated nanospheres represents a new paradigm for the optomechanical cooling of a small mechanical oscillator, with the prospect of realising quantum oscillators with unprecedentedly high quality factors.

• We investigate the dynamics of this system, especially in the so-called self-trapping regimes, where one or more optical fields simultaneously trap and cool the mechanical oscillator.
• The determining characteristic of this regime is that both the mechanical frequency $\omega_M$ and single-photon optomechanical coupling strength parameters $g$ are a function of the optical field intensities, in contrast to usual set-ups where $\omega_M$ and $g$ are constant for the given system.
• We also measure the characteristic transverse and axial trapping frequencies of different sized silica nanospheres in a simple optical standing wave potential, for spheres of radii $r=20-500$\,nm, illustrating a protocol for loading single nanospheres into a standing wave optical trap that would be formed by an optical cavity.