Quantum structure and dynamics for atom galleries

The bound state structure and dynamics for an atom trap formed from the whispering gallery modes (WGMs) of a dielectric microsphere are investigated. The coupling of the quantized internal and external atomic degrees of freedom plays a fundamental role in the quantum dynamics of this atom gallery. The radiative processes for a cold atom near a microsphere are modified due to the special symmetry of the atom gallery, the WGM mode structure, and the finite extent of the center-of-mass (c.m.) wave packet. Finally, interesting implications of the quantized c.m. for atomic matter waves and cavity QED with a quantum field are mentioned

Well-dressed states for wave-packet dynamics in cavity QED

The quantization of atomic center-of-mass motion is considered within the context of cavity QED with particular emphasis on the dynamics of localized wave packets. “Well-dressed” states are introduced as an eigenbasis that incorporates both the quantized atom-field interaction and the external bound states of a potential well. The interplay of internal and external time scales generates qualitatively new dynamics such as novel “collapses” and “revivals.

Cavity QED with whispering gallery modes of fused-silica microspheres

The Whispering Gallery Modes (WGMs) of fused silica microspheres hold the promise for simultaneous acheivement of high Q ( > 10^9) and small mode volumes (≾ 10^(-14) m^3) necessary for strong coupling in cavity QED. Here we present results for high Q measurements into the MR along with some progress towards experimental implementation in cavity QED

High-Q measurements of fused-silica microspheres in the near infrared

Measurements of the quality factor Q ~ 8 x 10^9 are reported for the whispering-gallery modes (WGM’s) of quartz microspheres for the wavelengths 670, 780, and 850 nm; these results correspond to finesse F ~ 2.2 x 10^6. The observed independence of Q from wavelength indicates that losses for the WGM’s are dominated by a mechanism other than bulk absorption in fused silica in the near infrared. Data obtained by atomic force microscopy combined with a simple model for surface scattering suggest that Q can be limited by residual surface inhomogeneities. Absorption by absorbed water can also explain why the material limit is not reached at longer wavelengths in the near infrared

Trapping of single atoms in cavity QED

By integrating the techniques of laser cooling and trapping with those of cavity quantum electrodynamics (QED), single Cesium atoms have been trapped within the mode of a small, high finesse optical cavity in a regime of strong coupling. The observed lifetime for individual atoms trapped within the cavity mode is $\tau \approx 28$ms, and is limited by fluctuations of light forces arising from the far-detuned intracavity field. This initial realization of trapped atoms in cavity QED should enable diverse protocols in quantum information science.Comment: 4 pages, 4 figure

Cavity QED with high-Q whispering gallery modes

We report measurements of cavity-QED effects for the radiative coupling of atoms in a dilute vapor to the external evanescent field of a whispering-gallery mode (WGM) in a fused silica microsphere. The high Q (5 x 10^(7)), small mode volume (10^(-8) cm^(3)), and unusual symmetry of the microcavity evanescent field enable velocity-selective interactions between fields with photon number of order unity in the WGM and (N) over bar(T) similar to 1 atoms in the surrounding vapor

Optimal Sizes of Dielectric Microspheres for Cavity QED with Strong Coupling

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, and critical atom number, N, cannot be minimized simultaneously, so that an "optimal" sphere size is taken to be the radius for which the geometric mean, (n x N)^(1/2), 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 (852nm) using fused-silica microspheres, for which the maximum coupling coefficient g/(2*pi)=750MHz occurs for a sphere radius a=3.63microns corresponding to the minimum for n=6.06x10^(-6). By contrast, the minimum for N=9.00x10^(-6) occurs for a sphere radius of a=8.12microns, while the optimal sphere size for which (n x N)^(1/2) is minimized occurs at a=7.83microns. On an experimental front, we have fabricated fused-silica microspheres with radii a=10microns and consistently observed quality factors Q=0.8x10^(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.Comment: 12 pages, 14 figure

Cavity QED with whispering gallery modes of fused-silica microspheres

The Whispering Gallery Modes (WGMs) of fused silica microspheres hold the promise for simultaneous acheivement of high Q ( > 10^9) and small mode volumes (≾ 10^(-14) m^3) necessary for strong coupling in cavity QED. Here we present results for high Q measurements into the MR along with some progress towards experimental implementation in cavity QED

Cooling of a single atom in an optical trap inside a resonator

We present detailed discussions of cooling and trapping mechanisms for an atom in an optical trap inside an optical cavity, as relevant to recent experiments. The interference pattern of cavity QED and trapping fields in space makes the trapping wells distinguishable from one another. This adds considerable flexibility to creating effective trapping and cooling conditions and to detection possibilities. Friction and diffusion coefficients are calculated in and beyond the low excitation limit and full 3-D simulations of the quasiclassical motion of a Cs atom are performed.Comment: One more figure and one more autho

Quantum Communication with Phantom Photons

We show that quantum information may be transferred between atoms in different locations by using ``phantom photons'': the atoms are coupled through electromagnetic fields, but the corresponding field modes do not have to be fully populated. In the case where atoms are placed inside optical cavities, errors in quantum information processing due to photon absorption inside the cavity are diminished in this way. This effect persists up to intercavity distances of about a meter for the current levels of cavity losses, and may be useful for distributed quantum computing.Comment: 6 pages RevTex, 4 eps figures included. Revised calculation with more details about mode structure calculation and the introduction of losse