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

z
y
x
magnetically trapped atoms
crossed beam dipole trap
Figure 4.3: Schematic of crossed laser beams above a cloud of magnetically
trapped atoms. Gravity is in the −ˆz direction as shown in the figure.
a magnetic field gradient of B ′ = 72 G/cm (see Sec. 2.4 for a definition of
this constant). Each dipole beam had 3.5 W of power and a 1/e 2 waist of
approximatly 150µm.
As shown in Fig. 4.4 a small dimple is evident on the right hand side
of the potential, however it is too small to create a bound state. Observe
that another state, |F = 1,mF = 1〉, does have a bound state under identical
conditions. The potential landscapes for the two states are shown in Fig. 4.5.
The reason for formation of the bound state is that the magnetic tilt is only
half of the value of the |F = 2,mF = 2〉 state.
To transfer atoms from the magnetic trap into the optical trap, we
added a depopulation beam parallel to a dipole beam. During the experimen-
139
g