Levitated Optomechanics in a hybrid electro-optical trap

This thesis describes the progress made in trapping and cooling silica nanoscale particles, in a hybrid electro-optical trap. The light field of a high finesse Fabry-Perot cavity and the quadrupole field generated by an rf Paul trap are used for the first time to both trap and cool naturally charged 209 nm dielectric nanospheres in high vacuum. Particles are first loaded into the Paul trap at pressures of 10^-1 mbar, after which their centre-of-mass motion is damped via optomechanical cooling, as the pressure is lowered to 10^-6 mbar. The combined ion trap-optical cavity set-up exposes an interesting interplay between the ion trap dynamics and the cavity mode which lead to a novel optomechanical cooling mechanism of a cyclic nature. This eliminates the need for a second, dedicated cooling mode from the cavity, or feedback cooling in order to cool the levitated particles to the ground state. At the same time, we identify a previously unobserved shift of the Paul trap secular frequencies due to the optical cavity, which enables readout of key parameters, such as the nanoparticles charge and the mean number of photons in the cavity. The dynamical features of the levitated particle, driven by linear and nonlinear optomechanical coupling, are observed through the cavity output, as well as the light scattered by the particle. As the background pressure is lowered, we observe greater than 1000 fold reduction in the centre-of-mass temperature of particles, before temperatures fall below the read-out sensitivity of the set-up