By Michael Schirber-<br><br>Cutting-edge electronic cooling devices work by having hot electrons tunnel from a metal to a superconductor, carrying heat with them. A new design, which has a “drain” for removing hot particles in the superconductor, has cooled a micrometer-sized metal slab from ∼150 millikelvin (mK) to a record temperature of less than 30 mK. Devices based on this scheme could potentially be installed directly on a chip for cooling qubits or ultrasensitive low-temperature detectors. <br><br>The basic structure in these electronic coolers consists of two NIS (normal metal-insulator-superconductor) junctions. When voltage is applied, relatively high-energy (hot) electrons flow out of the metal and into one superconductor, while lower-energy (cooler) electrons flow in from a second superconductor. Using this technique, previous work has been able to cool a small metal piece from 100 to 40 mK. However, the scheme’s cooling potential is diminished by heat leaking back into the metal, in particular, from hot “quasiparticles” (electron-hole pairs) that reside in the superconductors.<br><br><a href="http://physics.aps.org/synopsis-for/10.1103/PhysRevApplied.2.054001">READ MORE ON PHYSICS | AMERICAN PHYSICAL SOCIETY</a><br><br>Ref: <a href="http://link.aps.org/doi/10.1103/PhysRevApplied.2.054001">Sub-50-mK Electronic Cooling with Large-Area Superconducting Tunnel Junctions</a> | H. Q. Nguyen, M. Meschke, H. Courtois, and J. P. Pekola | <a href="http://link.aps.org/doi/10.1103/PhysRevApplied.2.054001">Phys. Rev. Applied 2, 054001 (2014)</a><br>
