Kerr-enhanced optomechanics

The pursuit of ground state cooling a mechanical mode has been of significant interest for its fundamental relevance to numerous quantum science and technology applications. In recent years, optomechanical backaction cooling protocols have successfully achieved the motional quantum ground state of a mechanical oscillator in the resolved sideband regime, i.e. when the mechanical resonance frequency is significantly larger than the cavity decay rate. However, as the size of these mechanical systems increases, their natural frequency generally decreases, pushing them into the unresolved sideband regime. Backaction cooling becomes less effective in this regime, limiting the ability to cool the mechanical mode to its ground state.

In this thesis, we theoretically study a novel optomechanical setup, where a nonlinear cavity and a mechanical cantilever are inductively coupled. Despite being initially proposed to achieve single-photon coupling strengths, this system has the particularity of being able to more efficiently backaction cool a mechanical mode in the unresolved sideband regime. We will demonstrate that the intrinsic nonlinearity of the cavity results in an enhancement of the cooling capabilities in the sideband unresolved regime as experimentally shown in D. ... mehrZoepfl et al. (PRL, 2023). The above arises due to the increased asymmetry between the cooling and heating processes, thereby improving the cooling efficiency.