A dual current source designed to provide static flux biases for a superconducting qubit and Superconducting QUantum Interference Device (SQUID) was analyzed. The source combined digitally programmable potentiometers with a stabilized voltage source. Each channel has maximum output of ∓1 mA and both current supplies are computer controlled. They were designed not to inject digital noise into the quantum bit and SQUID during manipulation and measurement of the flux. For a 275μA setting, the measured noise current was found 2.6 parts per million (ppm) rms in a bandwidth of 0.0017 Hz and by resetting the current in every 10 minutes the drift can be reduced to 5 ppm at a current of 750μA.
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