Magnetic Trapping
Magnetic trapping is created by adding a spatially varying magnetic quadrupole field to the red detuned optical field needed for laser cooling. This causes a Zeeman shift in the magnetic-sensitive mf levels, which increases with the radial distance from the centre of the trap. Because of this, as an atom moves away from the centre of the trap, the atomic resonance is shifted closer to the frequency of the laser light, and the atom becomes more likely to get a photon kick towards the centre of the trap.
The direction of the kick is given by the polarisation of the light, which is either left or right handed circular giving different interactions with the different mf levels. The correct polarisations are used so that photons moving towards the centre of the trap will be on resonance with the correct shifted atomic energy level, always driving the atom towards the centre.
Read more about this topic: Magneto-optical Trap
Famous quotes containing the word magnetic:
“We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.”
—Henry David Thoreau (1817–1862)