Experiments with Supersonic Beams as a Source of Cold Atoms

place inside a dilution refrigerator adds significant cost and complexity to the exper-
iment. Optical access to the trapped sample is also limited because of the cryogenic
environment. This lack of access limits the experiments which can be performed, as
well as the ability to effectively observe the sample. Thus, a general method which
is able to trap the sample in a room temperature chamber with good optical access
would decrease complexity, while enhancing the experimental utility of the apparatus.
1.2 Methods of Controlling Supersonic Beams
Because supersonic beams make excellent sources of cold atoms, numerous
groups have developed methods to control atoms and molecules cooled by supersonic
beams. The challenge is that while the atoms or molecules have been cooled by the
expansion, they are still moving fast in the lab frame. Even in this form, supersonic
beams are a staple of physical chemistry [8–10]. For many experiments though, the
high speed of the beams is a serious detriment, which has led to many efforts to
control the motion of supersonic beams.
One approach to controlling the beam is to employ mechanical methods. The
velocity of the supersonic flow is relative to the nozzle, not the vacuum chamber itself,
suggesting that it should be possible to produce slower beams by moving the nozzle
opposite to the expansion. This is the approach taken by Gupta and Hershbach [11],
who mounted their nozzle at the end of a rapidly rotating arm. Further mechanical
control methods have included focusing by reflecting the beams from bent crystals
[12], and stopping via collisions between atoms in crossed beams [13].
Another approach is to use external fields to control the motion of atoms or
molecules in the beam. Pulsed laser fields have been used to stop atoms in a beam
[14]. Pulsed electric fields are used to slow and trap molecules with permanent electric
dipole moments [15–17]. The pulsed electric field approach is also used to slow and
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