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Optimal sizes of dielectric microspheres for cavity QED with strong coupling

Buck, J. R. and Kimble, H. J. (2003) Optimal sizes of dielectric microspheres for cavity QED with strong coupling. Physical Review A, 67 (3). Art. No. 033806. ISSN 1050-2947. doi:10.1103/PhysRevA.67.033806.

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The whispering gallery modes (WGMs) of quartz microspheres are investigated for the purpose of strong coupling between single photons and atoms in cavity quantum electrodynamics (cavity QED). Within our current understanding of the loss mechanisms of the WGMs, the saturation photon number n₀ and critical atom number N₀ cannot be minimized simultaneously, so that an “optimal” sphere size is taken to be the radius for which the geometric mean √n₀xN₀, is minimized. While a general treatment is given for the dimensionless parameters used to characterize the atom-cavity system, detailed consideration is given to the D₂ transition in atomic cesium at λ₀ = 852nm using fused-silica microspheres, for which the maximum coupling coefficient g_a/(2π) ≈ 750MHz occurs for a sphere radius a = 3.63μm corresponding to the minimum for n₀ ≈ 6.06×10⁻⁶. By contrast, the minimum for N₀ ≈ 9.00×10⁻⁶ occurs for a sphere radius of a = 8.12μm, while the optimal sphere size for which √n₀xN₀ is minimized occurs at a = 7.83μm. On an experimental front, we have fabricated fused-silica microspheres with radii a ∼ 10μm and consistently observed quality factors Q ≥ 0.8×10⁷. These results for the WGMs are compared with corresponding parameters achieved in Fabry-Perot cavities to demonstrate the significant potential of microspheres as a tool for cavity QED with strong coupling.

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Additional Information:©2003 The American Physical Society (Received 18 October 2002; published 21 March 2003) We thank K. Birnbaum, S. J. van Enk, C. Hood, V. Ilchenko, A. Kuzmich, R. Legere, P. Lodahl, T. Lynn, H. Mabuchi, J. McKeever, T. Northup, D. Vernooy, and J. Ye for helpful discussions. This work was supported by the National Science Foundation, by the Office of Naval Research, and by the Caltech MURI on Quantum Networks administered by the Office of Army Research.
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Army Research Office (ARO)UNSPECIFIED
Subject Keywords:quantum electrodynamics; dielectric properties; quantum optics
Issue or Number:3
Classification Code:PACS: 42.55.Sa, 42.50.Ct, 32.80.-t
Record Number:CaltechAUTHORS:BUCpra03
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1935
Deposited By: Archive Administrator
Deposited On:23 Feb 2006
Last Modified:08 Nov 2021 19:43

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