Active position stabilization of an atomic cloud in a narrow-line magneto-optical trap using a Raspberry Pi.

We report on a simple method for an active position stabilization of an atomic cloud trapped in a magneto-optical trap operating on the narrow 182 kHz intercombination line of atomic ytterbium. Our method makes use of the significant sensitivity of the position of a narrow-line magneto-optical trap (MOT) on the laser frequency. After in situ detection of the MOT position using a Pi Camera, an error signal is generated by a Raspberry Pi, which is directly fed back onto the laser frequency. Thus, perturbations of the MOT position, e.g., due to drifts of the Zerodur cavity to which the MOT laser is stabilized or the ambient magnetic field, can be compensated directly. Our method allows for long-term stabilization of the MOT position on a 10 µm scale and thus improves loading of a tightly focused optical trap.