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

the constant rate at which atoms are depopulated from the magnetic trap, the
Figure 4.29: Atom accumulation in the optical trough as a function of the
current in the quadrupole coils. Vertical lines indicate the point at which
the magnetic field gradient produced by the current is no longer sufficient to
levitate atoms against gravity for atoms in the mF = 1 and mF = 2 magnetic
substates.
loading rate into the optical trough is clearly non-linear. This graph indicates
that atoms are more efficiently loaded at the end of the cooling sequence, when
the magnetic field gradient is low. This trend may be explained as follows.
As the magnetic gradient is reduced, atoms in the magnetically anti-trapped
|F = 1,mF = 1〉 state gain less energy as they travel from the depopulation
beam to the optical trough vertex or walls. Therefore a smaller fraction of
these atoms will have sufficient energy to push through the bottom or sides of
the trough’s potential. Also, at lower magnetic field gradients the magnetically
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