Cavity cooling of free nanoparticles in high vacuum

Cavity cooling has been successfully applied to single atoms, ions and atomic ensembles. It is however, most indispensable for larger and more complex particles, where direct laser cooling techniques are not applicable. We demonstrate cavity cooling of a silicon nanoparticle with a reduction of the transverse kinetic energy by a factor of over 30 [Asenbaum, P. et al. Nat. Commun. 4:2743]. Utilizing a pulsed laser we create and launch silicon nanoparticles beneath a high finesse cavity in high vacuum environment. While the particles transit through the intense cavity field the transverse velocity is reduced. By detecting the scattered light from the particle we can trace its movement in real time. Advancing this technique will be crucial to enable quantum coherence experiments with nanoparticles.