Suppressing Rayleigh Scatter in Levitated Optomechanics

Levitated Optomechanics uses a single nanoparticle, held in vacuum at the focus of a laser, as a platform for precision measurement. International effort now lies in attempting to reach the quantum regime using these and related systems in order to be utilised as sensors of weak external perturbations such as the gravitational field. Levitated nanoparticles are a promising route towards far exceeding the sensitivities of currently existing technologies. However, these advanced sensing applications require the creation of large spatial superpositions of the nanoparticle, which suffers from rapid decoherence. In particular, levitated particles are subject to decoherence from the laser itself; the laser photons which the particle scatters, randomly perturb its motion.

The main objective of the project is to demonstrate the suppression Rayleigh scattered light as a key source of decoherence in levitated optomechanics. To do this, I will aim to design and construct an experiment which will utilise a hemispherical mirror to suppress Rayleigh scatter by destructive interference. I may also explore the potential applications of the system to advanced sensing and more fundamental questions regarding how the laws of quantum mechanics operate on the macroscopic scale.