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

Abstract

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

To appear in Review of Scientific Instruments

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Cited by in corpus (5)

• Active stabilization of kilogauss magnetic fields to the ppm level for magnetoassociation on ultranarrow Feshbach resonances
• Optically trapped Feshbach molecules of fermionic 161Dy and 40K
• Experimental observation of the avoided crossing of two $S$-matrix resonance poles in an ultracold atom collider
• Bidirectional, Analog Current Source Benchmarked with Gray Molasses-Assisted Stray Magnetic Field Compensation
• Microscopy of an ultranarrow Feshbach resonance using a laser-based atom collider: A quantum defect theory analysis