A digital feedback controller for stabilizing large electric currents to the ppm level for Feshbach resonance studies.

摘要: Magnetic Feshbach resonances are a key tool in the field of ultracold quantum gases, but their full exploitation requires generation large, stable magnetic fields up to 1000 G with fractional stabilities better than 10-4. Design considerations for electromagnets producing these fields, such as optical access and fast dynamical response, mean that electric currents excess 100 A often needed obtain requisite strengths. We describe simple digital proportional-integral-derivative current controller constructed using field-programmable gate array off-the-shelf evaluation boards allows gain scheduling, enabling optimal control sources non-linear actuators. Our can stabilize an 337.5 level 7.5 × 10-7 averaging time 10 min bandwidth 2 kHz.