Quantum optomechanics in a room-temperature environment with levitated nanoparticles
Owing to its excellent isolation from the thermal environment, an optically levitated silica nanoparticle in ultra-high vacuum has been proposed as a promising candidate to achieve quantum behavior of massive objects at room temperature, with applications ranging from sensing to testing fundamental physics. As a first step towards quantum state preparation of the nanoparticle motion, both cavity and feedback cooling methods have been used to attempt cooling to its motional ground state, albeit with many technical difficulties. We have recently developed a new experimental interface, which combines stable (and arbitrary) trapping potentials of optical tweezers with the cooling performance of optical cavities, and demonstrated operation at desired experimental conditions. Even in such a reliable system ground state cooling has so far been elusive, mostly due to high laser phase noise at low motional frequencies and co-trapping by the cavity associated with high intracavity photon number. These problems have been resolved by implementing a new cooling method – cavity cooling by coherent scattering – which we employ to finally demonstrate ground state cooling of the nanoparticle motion. In this talk I will describe cavity cooling by coherent scattering and compare its performance to standard (dispersive) optomechanical interaction. I will present our latest experimental results and provide a brief outlook into potential quantum experiments with levitated nanoparticles.