Anna Clark, Anthony Williams, Steve Ruggiero, Marcel L. van den Berg, Joel N. Ullom
We demonstrate a thin-film, solid-state refrigerator based on the removal of hot electrons from a metal by quantum-mechanical tunneling. We have halved the electronic temperature in a macroscopic film from 260 mK to near 130 mK. Both the cooling power and temperature reduction of this refrigerator are well matched to cooling thin-film photon sensors. This advance was made possible by a new device design that removes the work of refrigeration more efficiently than previous efforts. Our refrigerator may make high-performance cryogenic sensors more accessible to the astronomical and analytical communities.