RESUMO
Experiments directed toward the realization of frequency standards of high accuracy using stored ions are briefly summarized. In one experiment, an RF oscillator is locked to a nuclear spin-flip hyperfine transition (frequency approximately 3.03x10(8) Hz) in (9 )Be(+) ions that are stored in a Penning trap and sympathetically laser-cooled. Stability is better than 3x10(-12)tau(-(1/2)) and uncertainty in Doppler shifts is estimated to be less than 5x10(-15). In a second experiment, a stable laser is used to probe an electric quadrupole transition (frequency approximately 1.07x10(15) Hz) in a single laser-cooled (199)Hg(+) ion stored in a Paul trap. The measured Q value of this transition is approximately 10(13). Future possible experiments are discussed.
RESUMO
Combining the measured binding energies of four of the most weakly bound rovibrational levels of the 87Rb2 molecule with results of two other recent high-precision experiments, we obtain exceptionally strong constraints on the atomic interaction parameters in a highly model independent analysis. The comparison of (85)Rb and (87)Rb data, where the two isotopes are related by a mass scaling procedure, plays a crucial role. We predict scattering lengths, clock shifts, and Feshbach resonances with an unprecedented level of accuracy. Two of the Feshbach resonances occur at easily accessible magnetic fields in mixed-spin channels. One is related to a d-wave shape resonance.