Using nanoengineering to enhance laser refrigeration of nanoparticles

We were interested in identifying design of nanoparticles that will enhance their refrigeration efficiency. We focused on maximizing their quantum yield while minimizing their non-radiative processes. In particular, we developed nanocrystals with and without an inert shell. We characterized the refrigeration efficiency by monitoring the temperature of the nanocrystals optically trapped in vacuum. Overall, we saw an increase in refrigeration efficiency for the shelled nanoparticle with a minimum temperature of ~150K. We will also show works towards controlling the motional temperature of the levitated nanoparticle paving the way towards absolute cooling in levitated optomechanics.