title: Electronic refrigeration at the quantum limit.
abstract: We demonstrate quantum-limited electronic refrigeration of a metallic island in a low-temperature microcircuit. We show that matching the impedance of the circuit enables refrigeration at a distance, of about 50 microm in our case, through superconducting leads with a cooling power determined by the quantum of thermal conductance. In a reference sample with a mismatched circuit this effect is absent. Our results are consistent with the concept of electromagnetic heat transport. We observe and analyze the crossover between electromagnetic and quasiparticle heat flux in a superconductor.
authors.affiliation: Low Temperature Laboratory, Helsinki University of Technology, 02015 TKK, Finland.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Timofeev
authors.forename: Meri
authors.initials: M
authors.lastname: Helle
authors.forename: Matthias
authors.initials: M
authors.lastname: Meschke
authors.forename: Mikko
authors.initials: M
authors.lastname: Möttönen
authors.forename: Jukka P
authors.initials: JP
authors.lastname: Pekola