Diabolical Points in Multi-Scatterer Optomechanical Systems
Update: 2016-02-02 14:06:18      Author: yangjuan@csrc.ac.cn

Optomechanical system, where radiation modes interact with mechanical elements, are receiving growing attention due to their promising applications as ultrasensitive sensors, quantum information processing elements and for preparing motional quantum states of large-scale structures. Remarkably, the ground-state cooling of the center-of-mass motion of a mechanical element was recently achieved. While the most basic optomechanical setup comprises of a driven optical cavity interacting with a mechanical mode, systems with multiple optical and mechanical modes offer much greater flexibility, and are currently actively investigated. Such more complex configurations can also give rise to phenomena that are qualitatively different from standard optomechanics.

A recent investigation [1] involving Stefano Chesi of CSRC and collaborators from ITP (Beijing) and Macquarie University has explored the occurrence of diabolical points in optomechanical systems. Suitable geometries of toroidal cavities with multiple scatterers were identified, where such singularities are shown to appear. The proposed configurations are relatively simple, being already close to several existing optomechanical setups. While the optomechanical coupling is usually derived by linearization in the (small) mechanical displacement, the coupling at such diabolical points would be necessarily non-analytic, since it is associated with an intrinsic singularity of the spectrum. The mechanical motion of the scatteres would make it possible to explore the conical spectrum and topological Berry phase associated to the diabolical point, as well as realize coherent transduction of photons in the two optical branches.

[1] S. Chesi, Y.-D. Wang, and J. Twamley, “Diabolical points in multi-scatterer optomechanical systems”, Scientific Reports 5, 7816 (2015), (pub. 15 January 2015). DOI: 10.1038/srep07816


Fig. 1 (a): Schematics of a toroidal cavity with multiple scatterers. (b): Conical intersection in the optical spectrum. (c): Positions of diabolical points (black/white dots) as functions of the displacements of two of the scatterers. Different types of mechanical trajectories (A, B, C) of these two scatterers are illustrated.

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