Sydney, Dec 8 (IANS) Physicists have devised a thermometre that can potentially gauge temperatures as ultracold as tens of trillionths of a degree above absolute zero.
Absolute zero is the lowest possible temperature, minus 273.15 degrees Celsius, in which all molecular activity ceases.

Scientists can currently cool atoms to a few billionths of a degree, but even this is too hot for certain applications.

For example, Richard Feynman of Harvard University dreamt of using ultracold atoms to simulate the complex quantum mechanical behaviour of electrons in certain materials.

This would require the atoms to be lowered to temperatures at least a hundred times colder than what has ever been achieved.

Unfortunately, thermometers that can measure temperatures of a few billionths of a degree rely on physics that doesn’t apply at these extremely low temperatures.

Now a team at the MIT-Harvard Centre for Ultra-Cold Atoms has developed a thermometer that can work in this unprecedentedly cold regime, said a Harvard statement.

The trick is to place the system in a magnetic field, and then measure the atoms’ average magnetisation.

While physicists demonstrated the method on atoms cooled to one billionth of a degree, they also showed that it should work for atoms hundreds of times cooler. Their experiment is reported in the latest issue of Physical Review Letters.