This is pretty much what we do to apply small bias currents to our superconducting circuits. The signals are small (<1 uA), and the power is dissipated outside

This is pretty much what we do to apply small bias currents to our superconducting circuits. The signals are small (<1 uA), and the power is dissipated outside of the cryostat, so this method is very simple and effective. The voltage and resistors don’t even need to be that huge, ~10 MOhm or below, and correspondingly, <10 V.