A magnetic persistent current switch at milliKelvin temperatures

We report the development of a magnetically driven Persistent Current Switch operated in a dilution refrigerator. We show that it can be safely used to charge a 60 mH coil with 0.5 A at 11 mK, which heats up the dilution refrigerator to 60.5 mK. Measurements at 4 K on a 440 μH coil reveal a residual resistance of R⩽3.3 pΩ.