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Ultracold circuits

Ultracold Circuits

Cooling materials to extremely low temperatures is important for basic physics research as well as for technological applications. By improving a special refrigerator and a low-temperature thermometer, Basel scientists have now managed to cool an electric circuit on a chip down to 220 microkelvin – close to absolute zero.

When materials are cooled down to extremely low temperatures, their behaviour often differs strongly from that at room temperature. A well-known example is superconductivity: below a critical temperature some metals and other substances conduct electric current without any losses. At even lower temperatures additional quantum-physical effects can occur, which are relevant for basic research as well as for applications in quantum technologies.

However, to reach such temperatures – less than a thousandth of a degree above the absolute zero of 0 Kelvin, or -273.15 degrees Celsius – is exceedingly difficult. Physicists in the research group of Prof. Dr. Dominik Zumbühl at the University of Basel, together with colleagues at the VTT Technical Research Centre in Finland and at Lancaster University in England, have now set a new low-temperature record. Their results have just been published in the scientific journal Physical Review Research.