Experiments to Control Atom Number and Phase-Space Density in ...

to magnetically trap an ensemble of rubidium atoms at a local magnetic field minimum,
if the atoms are in the low-field seeking states. This is routinely done in many cold atom
experiments [27].
Energy ShiftGHz
0.25
0.
0.25
0.5
0.75
0.5
0.25
25. 50. 75. 100. 125. 150. 175. 200. BGauss
Figure 2.8: Anomalous Zeeman shift of the hyperfine energy level structure in 87 Rb.
In lithium the anomalous Zeeman regime only extends for a few tens of Gauss,
even for the ground state. It is therefore important to understand the normal Zeeman
effect in addition to the anomalous Zeeman effect.
B
Figure 2.9: In the normal Zeeman effect regime the angular momentum spin J and
nuclear spin I precess around the external magnetic field axis individually.
I
As mentioned above, in the normal Zeeman regime the angular momentum J and
the nuclear spin I decouple and precess around the external magnetic field individually,
see figure 2.9. This happens when the interaction energy µ· B exceeds the fine structure
13
J