Laser collimation of a continuous beam of cold atoms using Zeeman-shift degenerate-Raman-sideband cooling

Abstract

In this article we report on the use of degenerate-Raman-sideband cooling for the collimation of a continuous beam of cold cesium atoms in a fountain geometry. Thanks to this powerful cooling technique we have reduced the atomic beam transverse temperature from 60 K to 1.6 K in a few milliseconds. The longitudinal temperature of 80 K is not modified. The flux density, measured after a parabolic flight of 0.57 s, has been increased by a factor of 4 to approximately 10 7 at. s −1 cm −2 and we have identified a Sisyphus-like precooling mechanism which should make it possible to increase this flux density by an order of magnitude.

Design Details of FOCS-2, an Improved Continuous Cesium Fountain Frequency Standard

“…This scheme has been tested successfully with FOCS-X to form the pre-cooling lattice "A" described shortly below. Other schemes studied with the same apparatus including grey molasses on the 32 component [21] and Zeemaninduced degenerate Raman sideband cooling (ZIDRSC) [19], [23]. We also demonstrated the use of 2D magneticallyinduced laser cooling as a means to compensate transverse magnetic fields in situ [24].…”

“…To achieve this, more atoms are launched to begin with thanks to a slow beam pre-source that loads the optical molasses [17], [18]. In addition, improved collimation based on optical lattices [19], [20], [21] means more atoms reach the detection zone after microwave interrogation. The design of FOCS-2 was inspired by experience acquired with FOCS-1 as well as input from auxiliary measurements performed on an experimental fountain dubbed FOCS-X that demonstrated an achievable gain in flux of at least 40.…”

Development of tuneable, narrow-band, and frequency stabilised laser heads in Observatoire Cantonal de Neuchâtel

“…In Observatoire Cantonal de Neuchâtel, the laser heads shown on figure 1 are employed for studying the basic interaction between atoms and photons, and in particular the effects of AC Stark shift [17], laser recoil induced resonances [18], Sisyphus, adiabatic and degenerate Raman sideband transverse laser cooling of cold atomic beams [19], etc.…”

Combined quantum-state preparation and laser cooling of a continuous beam of cold atoms

“…We used the procedure developped in Ref. [25] to obtain the [26]. Cold atoms are trapped in the potential wells of an optical lattice, their motion is quantized, and n is the vibrational quantum number.…”

“…In Ref. [25], we showed that it is possible to adapt this scheme to a continuous beam of cold atoms. However, the resulting quantum state |F = 3, m = 3 is not useful for an atomic clock and thus we would need to replace in this sideband cooling scheme the Zeeman shift by a Stark shift to accumulate all the atoms in |F = 3, m = 0 as proposed in Ref.…”