Low Noise Bipolar Current Source to Precisely Control Magnetic Fields in Ultra-cold Atoms Experiments*

Ultra-cold atom experiments often require a precise control over magnetic fields to provide a quantization axis and split the magnetic sublevels. A stable quadratic Zeeman effect is especially important in our experiments with sodium spinor Bose-Einstein condensates. It provides a sensitive knob that allows us to control entanglement generation via spin-exchange collisions. To better control the linear and quadratic Zeeman effects, we have constructed a low noise bipolar current source for three pairs of Helmholtz coils which create a uniform magnetic field at the center of the vacuum chamber. This analog-controlled current driver circuit can source or sink up to 8 A. This will allow us to tune and stabilize the magnetic field to an arbitrary value, which will result in a more precise control of spin-exchange collisions. In this poster, we provide an insight into the design of this current driver circuit.