Magneto-optical traps (MOTs) use a combination of lasers and magnetic fields to localize and cool neutral atoms to temperatures in the micro Kelvin regime. MOTs are essential for ultra-cold atoms research and have enabled extensive studies of Bose Einstein Condensates and Degenerate Fermi Gases.
To operate a MOT, two lasers need to be frequency locked such that they are slightly detuned to the red of the atomic transitions and stabilized to less than the 5 MHz natural transition linewidth. Locking offset from the actual transitions is easily achieved with the Thorlabs DAVS stabilized tunable laser. See the Stabilized Laser tab for more information. For more information about components featured in the MOT, see the System Components tab.
The image on the right shows the fluorescence of Rb atoms in the MOT cell, as detected by a CCD camera.
Figure 1 shows six beams of which three are right circularly polarized (σ+) and three are left circularly polarized (σ-). These six beams are necessary to provide confinement and cooling in three dimensions. For successful operation, two lasers have to be stabilized close to the Rubidium D2 transitions. One laser, often referred to as the "trap laser" and represented by (a) and (b) in the energy level diagram (Figure 2), provides the trapping forces. The second laser, known as the "re-pump laser" and represented by (c), (d), and (e) in Figure 2, ensures that the Rubidium atoms do not accumulate in the F=2 ground state, which cannot be accessed by the trap laser.
The Magneto-Optical Trap is under development and will be available soon. For more information, contact Tobias Paprotta.