Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions

J. Hätinen; A. Ronzani; R. P. Loreto; E. Mykkänen; A. Kemppinen; K. Viisanen; T. Rantanen; J. Geisor; J. Lehtinen; M. Ribeiro; J-P. Kaikkonen; O. Prakash; V. Vesterinen; W. Förbom; E. T. Mannila; M. Kervinen; J. Govenius; M. Prunnila

doi:10.1103/physrevapplied.22.064048

arXiv · 2403.08655

Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions

J. Hätinen·A. Ronzani·R. P. Loreto·E. Mykkänen·A. Kemppinen·K. Viisanen·T. Rantanen·J. Geisor·J. Lehtinen·M. Ribeiro·J-P. Kaikkonen·O. Prakash·V. Vesterinen·W. Förbom·E. T. Mannila·M. Kervinen·J. Govenius·M. Prunnila

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Abstract

Replacing the bulky cryoliquid-based cooling stages of cryoenabled instruments by chip-scale refrigeration is envisioned to disruptively reduce the system size similar to microprocessors did for computers. Electronic refrigerators based on superconducting tunnel junctions have been anticipated to provide a solution, but reaching the necessary above the 1-K operation temperature range has remained a goal out of reach for several decades. We show efficient electronic refrigeration by Al-AlO$_x$-Nb superconducting tunnel junctions starting from bath temperatures above 2 K. The junctions can deliver electronic cooling power up to approximately mW/mm$^2$, which enables us to demonstrate tunnel-current-driven electron temperature reduction from 2.4 K to below 1.6 K (34% relative cooling) against the phonon bath. Our work shows that the key material of integrated superconducting circuits - niobium - enables powerful cryogenic refrigerator technology. This result is a prerequisite for practical cryogenic chip-scale refrigerators and, at the same time, it introduces a new electrothermal tool for quantum heat-transport experiments.

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J. Hätinen, A. Ronzani, R. P. Loreto, E. Mykkänen, A. Kemppinen, K. Viisanen, T. Rantanen, J. Geisor, J. Lehtinen, M. Ribeiro, J-P. Kaikkonen, O. Prakash, V. Vesterinen, W. Förbom, E. T. Mannila, M. Kervinen, J. Govenius, M. Prunnila. 2024-03-13. Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions. https://doi.org/10.1103/physrevapplied.22.064048

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