Mika Prunnila: On-chip electron refrigeration for quantum technology

Numerous applications, from industrial non-destructive imaging through ultra-sensitive photon counting to various implementations of solid-state quantum computers require low temperatures for their sensor and processor chips. Replacing the bulky cryo-liquid based cooling stages of cryo-enabled instruments by chip scale refrigeration is envisioned to disruptively reduce the system size similarly as microprocessors did for computers. Chip scale cooling has been demonstrated with electronic refrigerators based on tunnel junctions in the sub-1 K temperature range, and just recently also above 2 K. In this colloquium I will discuss physics and recent approaches of chip scale refrigeration.