Showing papers by "James C. Bergquist published in 1987"

Laser-cooling limits and single-ion spectroscopy

Abstract: The limitations to the achievement of low kinetic energies for laser cooling of single ions confined in electromagnetic traps are discussed. Sideband cooling of an ion in an rf (Paul) trap is reexamined including the effects of finite laser bandwidth and the energy of the rf micromotion. The micromotion is the oscillatory motion of the ion at the same frequency as the rf voltage applied to the trap electrodes. Sideband cooling of ions in a Penning trap is examined for the first time. In both cases, cooling to the zero-point energy of the ion in the trap should be possible and a method for verifying this condition is suggested. The implications for high-resolution, high-accuracy spectroscopy are investigated. Under certain conditions, the uncertainty in the second-order Doppler shift may be significantly less than 1 part in ${10}^{18}$. .AE

Absorption spectroscopy at the limit: detection of a single atom.

Abstract: We investigate the sensitivity limit of absorption spectroscopy. An experiment is described in which the decrease in transmitted light intensity that is due to absorption by a single, electromagnetically confined atomic ion is observed.

Laser Spectroscopy of Trapped Atomic Ions

Abstract: Recent developments in laser spectroscopy of atomic ions stored in electromagnetic traps are reviewed with emphasis on techniques that appear to hold the greatest promise of attaining extremely high resolution. Among these techniques are laser cooling and the use of single, isolated ions as experimental samples. Doppler shifts and other perturbing influences can be largely eliminated. Atomic resonances with line widths of a few parts in 10(11) have been observed at frequencies ranging from the radio frequency to the ultraviolet. Experimental accuracies of one part in 10(18) appear to be attainable.

Radiative decay rates in Hg+ from observations of quantum jumps in a single ion.

Abstract: Radiative decay rates connecting the lowest four energy levels of $^{198}\mathrm{Hg}^{+}$ have been derived solely from an analysis of the fluctuations (quantum jumps) of the laser-induced fluorescence of the 194-nm first resonance transition of a single ion confined in a Paul trap. The natural linewidth of the 194-nm first resonance transition was also measured. The measured decay rates and branching ratios are in satisfactory agreement with theory.

Absolute Wavelength Measurements and Fundamental Atomic Physics

Abstract: The Rydberg constant ties together several areas of fundamental physics: fundamental constants; atomic and molecular theory; and spectroscopy of basic systems As determined at Yale, (Zhao et al[1]) R is the most precisely measured, fundamental constant[2]: R = 109 737315 73(3) [cm-1]