Nanomechanical testing of silica nanospheres for levitated optomechanics experiments

TL;DR

This study investigates the nanomechanical and optical properties of silica nanospheres used in levitated optomechanics, focusing on how annealing affects their elastic moduli and trap stability in high vacuum conditions.

Contribution

It introduces an annealing method to improve the elastic properties of silica nanospheres and analyzes how porosity and shape influence trapping stability in optomechanical experiments.

Findings

Annealing increases the elastic modulus of silica nanospheres.

Porosity and non-sphericity can cause trapping instabilities.

Optical trap lifetimes are affected by the nanospheres' structural properties.

Abstract

Optically-levitated dielectric particles can serve as ultra-sensitive detectors of feeble forces and torques, as tools for use in quantum information science, and as a testbed for quantum coherence in macroscopic systems. Knowledge of the structural and optical properties of the particles is important for calibrating the sensitivity of such experiments. Here we report the results of nanomechanical testing of silica nanospheres and investigate an annealing approach which can produce closer to bulk-like behavior in the samples in terms of their elastic moduli. These results, combined with our experimental investigations of optical trap lifetimes in high vacuum at high trapping-laser intensity for both annealed and as-grown nanospheres, were used to provide a theoretical analysis of the effects of porosity and non-sphericity in the samples, identifying possible mechanisms of trapping instabilities for nanospheres with non-bulk-silica-like properties.