Direct control of high magnetic fields for cold atom experiments based on NV centers

In cold atomic gases the interactions between the atoms are directly controllable through external magnetic fields. The magnetic field control is typically performed indirectly by stabilizing the current through a pair of Helmholtz coils, which produce this large bias field. Here, we overcome the limitations of such an indirect control through a direct feedback scheme, which is based on nitrogen-vacancy centers acting as a magnetic field sensor. This allows us to measure and stabilize fields of 4.66 mT down to 12 nT RMS noise over the course of 24 h, measured on a 1 Hz bandwidth. We achieve a control of better than 1 ppm after 20 minutes of integration time, ensuring high long-term stability for experiments. This approach extends direct magnetic field control to strong magnetic fields, which could enable new precise quantum simulations in this regime.