American scientists have achieved a new maximum in atomic clock precision using ytterbium atoms cooled down to near absolute zero temperatures.
Scientists at the National Institute of Standards and Technology (NIST), USA, developed and tested two sets of atomic clocks, synchronising them to nearly absolute values. By substituting conventional cesium by atoms of ytterbium, they have achieved ten times better stability.
The findings published in the recent issue of the Science journal are believed to open new possibilities in high-precision timekeeping, which is crucial, for example, for GPS satellites and related applications.
"The stability of the ytterbium lattice clocks opens the door to a number of exciting practical applications of high-performance timekeeping," said Dr Andrew Ludlow, a NIST physicist.
Thousands of ytterbium atoms cooled to 10 millionths of a degree above absolute zero - the coldest temperature possible - are trapped in a laser lattice. A transition between two energy levels in the atoms acts as the clock's pendulum that can go on almost indefinitely.
Every tick of these clocks matches the other set with nearly absolute precision. The ticks vary in length by less than two parts of a quintillion.
If the length of each tick is divided into a quintillion parts, two of those are the full extent by which a tick might lengthen or shorten.
In general, tick fluctuations are closely linked to the accuracy of atomic clocks - the more stable a clock's ticks are, the more precisely the atomic clock measures time.