Düsseldorf 2007 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 11: Quanteneffekte (QED)
Q 11.2: Talk
Monday, March 19, 2007, 14:30–14:45, 5E
An analogy to Cavity QED in scattering-induced modal coupling in a microsphere resonator — •Andrea Mazzei1, Leonardo Menezes2, Stephan Götzinger3, Vahid Sandoghdar3, and Oliver Benson1 — 1Humboldt Universität zu Berlin - AG Nanooptik, Hausvogteiplatz 5-7, 10117 Berlin — 2Departamento de Fìsica, Universidade Federal de Pernambuco, Brazil — 3Laboratory of Physical Chemistry, ETH Zürich - Switzerland
The basic system to study in Cavity QED is a single dipole emitter interacting with a single mode of an optical cavity. In a coupled system with damping, two main regimes can be distinguished: in the strong coupling regime the dynamics between, e.g. an atom and a cavity, is reversible: Rabi oscillations and mode splitting are observed. In the weak coupling regime the interaction with a continuum of states results in an irreversible decay of the dipole. In this paper we introduce an analogy between CQED effects (atom and cavity) and the modal coupling of high-Q modes in an optical microresonator induced by a Rayleigh scatterer. In our experiments a scanning probe is used as a controllable Rayleigh scatterer, which can be positioned with nanometer precision in the whispering-gallery modes of a microsphere resonator. By moving the scanning probe into the mode, the modal coupling constant can be controlled and the transition from weak to strong coupling was observed: the resonance splits into a doublet, with a frequency splitting proportional to the coupling rate. The developed theoretical analogy gives also an explanation for the surprisingly large modal splitting previously reported by other groups.