Ultrahigh-Q toroidal microresonators for cavity quantum electrodynamics
We investigate the suitability of toroidal microcavities for strong-coupling cavity quantum electrodynamics (QED). Numerical modeling of the optical modes demonstrate a significant reduction of the modal volume with respect to the whispering gallery modes of dielectric spheres, while retaining the high-quality factors representative of spherical cavities. The extra degree of freedom of toroid microcavities can be used to achieve improved cavity QED characteristics. Numerical results for atom-cavity coupling strength g, critical atom number No, and critical photon number no for cesium are calculated and shown to exceed values currently possible using Fabry-Perot cavities. Modeling predicts coupling rates g/2π exceeding 700 MHz and critical atom numbers approaching 10⁻⁷ in optimized structures. Furthermore, preliminary experimental measurements of toroidal cavities at a wavelength of 852 nm indicate that quality factors in excess of 10⁸ can be obtained in a 50-µm principal diameter cavity, which would result in strong-coupling values of (g/(2π),n(0),N-0) = (86 MHz, 4.6 x 10⁻⁴, 1.0 x 10⁻³).
Additional Information© 2005 The American Physical Society. Received 27 August 2004; published 26 January 2005. The work of K.J.V. was supported by DARPA, the Caltech Lee Center, and the National Science Foundation. The work of H.J.K. was supported by the National Science Foundation, by the Caltech MURI Center for Quantum Networks, by the Advanced Research and Development Activity, and by the California Institute of Technology.
Published - SPIpra05.pdf
Accepted Version - 0410218.pdf