Optimal sizes of dielectric microspheres for cavity QED with strong coupling

Journal Article · Sat Mar 01 04:00:00 EST 2003 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.67.033806· OSTI ID:20633882

Buck, J R; Kimble, H J ^[1]

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1. Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States)

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 n{sub 0} and critical atom number N{sub 0} cannot be minimized simultaneously, so that an 'optimal' sphere size is taken to be the radius for which the geometric mean {radical}(n{sub 0}N{sub 0}), 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 D{sub 2} transition in atomic cesium at {lambda}{sub 0}=852 nm using fused-silica microspheres, for which the maximum coupling coefficient g{sub a}/(2{pi}){approx_equal}750 MHz occurs for a sphere radius a=3.63 {mu}m corresponding to the minimum for n{sub 0}{approx_equal}6.06x10{sup -6}. By contrast, the minimum for N{sub 0}{approx_equal}9.00x10{sup -6} occurs for a sphere radius of a=8.12 {mu}m, while the optimal sphere size for which {radical}(n{sub 0}N{sub 0}) is minimized occurs at a=7.83 {mu}m. On an experimental front, we have fabricated fused-silica microspheres with radii a{approx}10 {mu}m and consistently observed quality factors Q{>=}0.8x10{sup 7}. 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.

• OSTI ID: 20633882
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 67; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
CESIUM
COUPLING
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
MHZ RANGE
MICROSPHERES
OPTICS
PHOTONS
QUALITY FACTOR
QUANTUM ELECTRODYNAMICS
QUARTZ
SILICA