High-performance electronic cooling with superconducting tunnel junctions

Abstract

International audienceWhen biased at a voltage just below a superconductor's energy gap, a tunnel junction between this superconductor and a normal metal cools the latter. While the study of such devices has long been focussed to structures of submicron size and consequently cooling power in the picoWatt range, we have led a thorough study of devices with a large cooling power up to the nanoWatt range. Here we describe how their performance can be optimized by using a quasi-particle drain and tuning the cooling junctions' tunnel barrier

Quasiparticle entropy in superconductor/normal metal/superconductor proximity junctions in the diffusive limit

“…Recently a growing interest has been put on the investigation of thermodynamic properties of nanosystems, where coherent effects can be both of fundamental interest and useful for applications. [1][2][3][4][5] In particular, superconductor junction systems have attracted interest, as they exhibit phase-dependent thermal transport enabling coherent caloritronic devices, 3,[6][7][8][9][10][11] and have properties useful for cooling systems in solid-state devices [12][13][14][15] . Conversely, they enable conversion between thermal currents and electric signals, leading to applications in electronic thermometry 3,16,17 and bolometric sensors and singlephoton detectors [18][19][20][21][22][23][24][25][26] .…”

Quantum Thermodynamics of Nanoscale Thermoelectrics and Electronic Devices

“…Most current experimental sub-Kelvin thermoelectric refrigerators rely on superconductors which are discussed in Refs. [5,32,74], although the refrigeration of microscopic semiconductor electron gases with quantum dots was also achieved some time ago [75].…”

Relaxation of Nonequilibrium Quasiparticles in Mesoscopic Size Superconductors

“…The drain should be 'isolated' from the superconductor with thin tunnel barrier, which from one side lets quasiparticles get efficiently trapped in the drain, while from another side, stops the inverse proximity effect. In particular, it has been demonstrated that electronic cooling can be optimized in specially-designed large area normal metalinsulator-superconductor junctions [105]. The two key ingredients were found to be of high importance: (i) the tunnel barrier transparency for the cooling junctions [106], (ii) the coupling to a quasiparticle drain, through a (separate) tunnel junction [107].…”