Department of Physics in collaboration with Swiss Nanoscience Institute succeeded in cooling a nano electric chip to temperature lower than 3 millikelvin. Actually, they wanted to make it closure to Absolute zero. Absolute zero is the lower limit of the thermodynamic temperature scale which is equal to -273.15 degree Celsius.
Other partners who collaborated in the research were from Finland and Germany. They used magnetic cooling to cool the electrical connections as well as the chip itself. The results were published in the journal Applied Physics Letters.
How they achieve it?
The group led by Basel physicist Professor Dominik Zumbühl had previously suggested that utilizing the principle of magnetic cooling in nanoelectronics in order to cool nanoelectronic devices to unprecedented temperatures close to absolute zero.
Magnetic cooling is the cooling down a system when magnetic field is ramped down avoiding external heat. Before ramping down, the heat of magnetization needs to be removed with another method to obtain efficient magnetic cooling.
“The combination of cooling systems allowed us to cool our chip down to below 3 millikelvin, and we are optimistic than we can use the same method to reach the magic 1 millikelvin limit,” says Zumbühl. It is also remarkable that the scientists are in a position to maintain these extremely low temperatures for a period of seven hours. This provides enough time to conduct various experiments that will help to understand the properties of physics close to absolute zero.
The team started by using magnetic cooling all the chip’s electric connections to 150 microkelvin then they integrated second cooling system directly into the chip and also placed a Coulomb blockade thermometer on it. This combination and material enabled scientists to make the temperature down to Absolute Zero.