title: Diabolical points in multi-scatterer optomechanical systems.
abstract: Diabolical points, which originate from parameter-dependent accidental degeneracies of a system's energy levels, have played a fundamental role in the discovery of the Berry phase as well as in photonics (conical refraction), in chemical dynamics, and more recently in novel materials such as graphene, whose electronic band structure possess Dirac points. Here we discuss diabolical points in an optomechanical system formed by multiple scatterers in an optical cavity with periodic boundary conditions. Such configuration is close to experimental setups using micro-toroidal rings with indentations or near-field scatterers. We find that the optomechanical coupling is no longer an analytic function near the diabolical point and demonstrate the topological phase arising through the mechanical motion. Similar to a Fabry-Perot resonator, the optomechanical coupling can grow with the number of scatterers. We also introduce a minimal quantum model of a diabolical point, which establishes a connection to the motion of an arbitrary-spin particle in a 2D parabolic quantum dot with spin-orbit coupling.
authors.affiliation: Beijing Computational Science Research Center, Beijing 100084, China.
authors.forename: Stefano
authors.initials: S
authors.lastname: Chesi
authors.affiliation: State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of SciencesP.O. Box 2735, Beijing 100190, China.
authors.forename: Ying-Dan
authors.initials: YD
authors.lastname: Wang
authors.affiliation: Centre for Engineered Quantum Systems, Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia.
authors.forename: Jason
authors.initials: J
authors.lastname: Twamley