Synthesis of High-Purity Solid SiO2 Nanodumbbells via Induced Aggregation

Optically levitated nanodumbbells in vacuum are excellent candidates for thermodynamics, macroscopic quantum mechanics, precision measurements and quantum sensing. Silica (SiO₂) material, with extremely low absorption of near-infrared light and super mechanical strength, has been the most potential material for optically levitated systems. Here we synthesize high-purity solid SiO₂ nanodumbbells via Stöber method by introducing acetone for the induced aggregation of SiO₂ nanospheres. The nanodumbbells show high uniformity and their sizes are tunable. Previous experimental results demonstrated that the synthetic nanodumbbells can be applied in GHz nanomechanical rotors and can withstand the tensile strength of over 13 GPa. This work supports batch production and high yield of SiO₂ nanodumbbells, which engineers a new material platform to advance levitated optomechanics.