Improved optomechanical interactions for quantum technologies: from hybrid membranes to optical levitation
Cavity optomechanics reached remarkable success in coupling optical and mechanical degrees of freedom. The standard mechanism relies on dispersive interaction wherein a cavity mode acquires a frequency shift proportional to the mechanical displacement. Efficient coupling is, however, often impeded by large cavity decay rates or strong heating of the mechanical element by optical absorption. In this talk, I will present two strategies to circumvent this problem. In the first one, a membrane doped with an ensemble of two-level emitters or patterned with a photonic-crystal structure is used as a mechanical element. The hybridization of the cavity mode with the membrane’s internal resonance leads to a modified response, resulting in an effective narrow cavity linewidth. I will show how such systems can be described quantum mechanically and discuss how optomechanical sideband cooling can be improved by the presence of the internal resonance. Second, I will discuss optomechanics with levitated particles and show how coherent scattering can be used to generate strong mechanical squeezing. In this system, the standard dispersive interaction is replaced by scattering of the trapping beam into an empty cavity mode. This process can result in strong, controllable coupling between the cavity mode and the motion of the particle with minimal absorption heating. I will also briefly outline how this type of interaction can be used to engineer coupling between different center-of-mass modes of the particle allowing, in principle, full optomechanical control of the particle motion.