scientists at the university of basel (switzerland) have successfully cooled a nanoelectronics chip to a temperature lower then three millikelvin, setting a new world record for the coldest chip thanks to a magnetic cooling process, according to a report from the university.

a chip with a coulomb blockade thermometer on it is prepared for experiments at extremely low temperatures. (university of basel, department of physics)

the team from basel used a pair of cooling techniques based on magnetic cooling to reach 150 microkelvin, which is only a thousandth of a degree away from absolute zero (zero degrees kelvin or -273.15°c).

“they then integrated a second cooling system directly into the chip itself, and also placed a coulomb blockade thermometer on it,” the article read. “the construction and the material composition enabled them to magnetically cool this thermometer to a temperature almost as low as absolute zero as well.”

by using both cooling approaches the scientists reached lower three millikelvins and they believe that the same method can be used to reach one millikelvin.

the article added, “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 research was recently published in applied physics letters. the abstract stated:

“cooling nanoelectronic devices below 10 mk is a great challenge since thermal conductivities become very small, thus creating a pronounced sensitivity to heat leaks. here, we overcome these difficulties by using adiabatic demagnetization of both the electronic leads and the large metallic islands of a coulomb blockade thermometer.

“this reduces the external heat leak through the leads and also provides on-chip refrigeration, together cooling the thermometer down to 2.8 ± 0.1 mk. we present a thermal model which gives a good qualitative account and suggests that the main limitation is heating due to pulse tube vibrations.

“with better decoupling, temperatures below 1 mk should be within reach, thus opening the door for μk nanoelectronics.”