Two distinct mechanisms are investigated for transferring a pure 87 Rb Bose-Einstein condensate in the |F = 2, m F = 2〉 state into a mixture of condensates in all the m F states within the F = 2 manifold. Some of these condensates remain trapped whilst others are output coupled in the form of an elementary pulsed atom laser. Here we present details of the condensate preparation and results of the two condensate output coupling schemes. The first scheme is a radio frequency technique which allows controllable transfer into available m F states, and the second makes use of Majorana spin flips to equally populate all the manifold sub-states. More recently, the production of multi-component condensates has revealed intriguing quantum fluid dynamics, and enabled precise measurement of relative quantum phase [9]. Experiments at JILA have focused on mixtures involving atoms in different ground state hyperfine levels (quantum number F), and coupling with a two photon (microwave plus radio frequency) transition. Experiments at MIT have used an optical dipole trap to confine a condensate occupying all magnetic sub-states (quantum number m F ) of the same hyperfine level [10]. Spin exchange processes result in domain formation which exhibits an anti-ferromagnetic interaction [11]. An important aspect of that work is the confinement of condensed atoms in sub-states which cannot be magnetically trapped.In this paper we present the results of two techniques for transforming a single state |F = 2, m F = 2〉 87 Rb Bose condensate into a mixture of all five magnetic sub-states of the F = 2 hyperfine level. Two of these states are magnetically confined (|2, 2〉 and |2, 1〉), with magnetic moments differing by a factor of 2, and the other states are unconfined.Applying an RF field similar to that used in the evaporative cooling stage of the experiment we can couple atoms between adjacent m F states. It is possible to control the number of atoms which are coupled from the |2, 2〉 state into the other m F states: condensates with predetermined sub-state populations can be constructed. For example, we can limit the transfer into untrapped states.

We have observed the narrow 1S-2S transition in hydrogen and deuterium with high resolution using Doppler-free two-photon absorption of continuous-wave 243-nm light. The transition frequencies were measured by direct comparison with accurately calibrated lines in the spectrum of the "Te2 molecule. We find the 1S-2S interval to be 2466061414.1(8) MHz in hydrogen and 2466732408.5(7) MHz in deuterium. By combining these results with recent measurements of the Rydberg constant we obtain the values 8172.6(7) and 8183.7(6) MHz for the 1S Lamb shifts in hydrogen and deuterium, respectively. These are the most precise measurements of the 1S Lamb shifts in these atoms and they are in excellent agreement with the theoretical values of 8173.03(9) and 8184.08(12) MHz. Alternatively, if the 1S Lamb shift is supposed known from theory, our measurements determine the Rydberg constant as R = 109 737.315 73 (3) cm Recently, the 1S-2S transition in hydrogen was observed using this source and its frequency was measured. ' By using an accurate value of the Rydberg constant it was possible to extract the Lamb shift. This calibration procedure is essentially the same comparison of hydrogen transitions used in the early experiments, but with several intermediate steps linking the two transitions. Our work at Oxford University" has concentrated on the development of frequency doubling as a means of generating cw 243-nm light because it offers the longterm prospect of a direct comparison of the 1S-2S and Balmer-P transitions. In this paper we describe the first experiment on hydrogen 1S-2S using cw 243-nm light generated by frequency doubling. ' ' We have measured the 1S-2S transition frequency f (1S-2S) in both hydrogen and deuterium. As in Ref. 9 our determination of the Lamb shift uses an indirect calibration via the Rydberg constant; however, the use of frequency doubling reduces the number of intermediate steps and by employing two lasers it was possible to calibrate the measurement using accurate heterodyne techniques.These improvements lead to a value of the hydrogen 1S Lamb shift which is a factor of 3 more precise than the previous value, and to the first cw measurement of the 1S Lamb shift in deuterium, improving the precision in this case by a factor of 50. An alternative interpretation of our measurements is pos-40 6169

No abstract

The structure of the resonance line ⋋553.5 nm of Ba ɪ has been studied by means of Doppler-free spectroscopy. Dye laser light was scattered resonantly from an atomic beam containing the natural mixture of isotopes; the spectra were recorded digitally and analysed by computer. The main object was to provide data to reduce uncertainties due to electronic calculations in the extraction of nuclear data from optical measurements. The isotope shifts (MHz), relative to 138 Ba, are 137 Ba, – 214.7 (5); 136 Ba, – 127.5 (13); 135 Ba, – 258.7 (7); 134 Ba, – 142.8 (12). The minus signs indicate that 138 Ba has the lower frequency in each case. These results are combined with muonic X-ray, electronic X-ray and other optical data to extract changes in mean square radius of the nuclear charge distribution. The hyperfine splitting factors 135 A and 135 B were found to be – 97.76 (14) MHz and 32.29 (47) MHz respectively. From an analysis of these and other results for the 6s6p configuration we obtain the quadrupole moment of 135 Ba (uncorrected for quadrupole shielding) to be 0.195 (40) barn (1 barn = 10 -28 m 2 ).

The output of a grating-stabilized external-cavity diode laser was injected into a semiconductor tapered amplifier in a master-oscillator power amplifier configuration, producing as much as 500 mW of power with narrow linewidth. The additional linewidth that is due to the tapered amplifier is much smaller than the typical linewidth of grating-stabilized laser diodes. To demonstrate the usefulness of the narrow linewidth and high output power, we used the system to perform Doppler-free two-photon spectroscopy with rubidium.