1. Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions
- Author
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Hätinen, J., Ronzani, A., Loreto, R. P., Mykkänen, E., Kemppinen, A., Viisanen, K., Rantanen, T., Geisor, J., Lehtinen, J., Ribeiro, M., Kaikkonen, J-P., Prakash, O., Vesterinen, V., Förbom, W., Mannila, E. T., Kervinen, M., Govenius, J., and Prunnila, M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Replacing the bulky cryo-liquid based cooling stages of cryo-enabled instruments by chip scale refrigeration is envisioned to disruptively reduce the system size similarly as microprocessors did for computers. Electronic refrigerators based on superconducting tunnel junctions have been envisioned to provide a solution, but reaching the necessary above 1 kelvin operation temperature range has remained a goal out of reach for several decades. We show efficient electronic refrigeration by Al-AlOx-Nb superconducting tunnel junctions starting from bath temperatures above 2 K. The junctions can deliver electronic cooling power up to $\sim$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 electro-thermal tool for quantum heat transport experiments.
- Published
- 2024