Swiss researchers set new record on coldest temperature

GENEVA, Dec. 21 (Xinhua) -- Swiss scientists have set a new world record on the coldest temperature by cooling a nano-electronic chip to 2.8 millikelvin, which is the closest to absolute zero ever reached before, according to a press release from the University of Basel on Thursday.

Even scientists like to compete for records, which is why numerous working groups worldwide are using high-tech refrigerators to reach temperatures as close to absolute zero as possible.

Absolute zero is 0 kelvin or -273.15 degrees Celsius. Physicists aim to cool their equipment to as close to absolute zero as possible, because these extremely low temperatures offer the ideal conditions for quantum experiments and allow entirely new physical phenomena to be examined.

Scientists from the Department of Physics at the University of Basel and the Swiss Nanoscience Institute used magnetic cooling to cool the electrical connections as well as the chip itself. The results were published in the journal Applied Physics Letters.

The research team utilized the principle of magnetic cooling in nanoelectronics in order to cool nano-electronic devices to unprecedented temperatures close to absolute zero. Magnetic cooling is based on the fact that a system can cool down when an applied magnetic field is ramped down while any external heat flow is avoided. Before ramping down, the heat of magnetization needs to be removed with another method to obtain efficient magnetic cooling.

The team successfully used a combination of two cooling systems, both based on magnetic cooling, to cool all of the chip's electrical connections to temperatures of 150 microkelvin, a temperature less than a thousandth of a degree away from absolute zero.

Achieving such low temperatures is not just an academic exercise. "Extremely low temperatures offer the ideal conditions for quantum experiments and allow entirely new physical phenomena to be examined," according to the press release. Enditem