Single-Photon Atomic Cooling - Raizen Lab - The University of ...

vacuum chamber used for atomic experiments. The two features, rapid MOT
loading and a long magnetic trap confinement time, are typically mutually
exclusive because the former is favored by a high background vapor pressure
while for the latter very low background pressures are required. The double
MOT configuration solves this problem by separating the chamber into two re-
gions, one of high pressure and one of low, connected by a differential pumping
tube. Atoms are rapidly loaded in the high pressure region and then “pushed”
with a resonant beam (the so-called push beam) into the low pressure region.
To this end, our chamber consists of an upper region maintained at the ru-
bidium vapor pressure, a lower chamber more than three orders of magnitude
lower in pressure, and a middle chamber which houses the pumps required to
maintain this pressure differential. The entire chamber is shown in Fig. 3.1.
This photograph was taken during a vacuum bakeout so the chamber is away
from the experiment, allowing a clear view of its elements. The three vacuum
chamber sections are indicated in the photograph.
3.1.1 Upper Chamber
The upper chamber serves as a high pressure region for quickly accu-
mulating 87 Rb atoms in a MOT which are then pushed into the lower chamber.
This function is served with a simple design consisting of three main elements:
a glass cell, a source of rubidium and a differential pumping tube connecting
the upper and lower chamber, as shown in Fig. 3.2.
The glass cell is constructed from a rectangular section of Pyrex glass
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