Berlin: In a new research work, a team of scientists has shown how optical atomic clocks in the future might become more compact and even portable, maybe even travel to space.
The research was done by scientists from the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany.
Optical clocks like the strontium clock in the PTB could be the atomic clocks of the future; some of them though are already ten times more precise and stable than the best primary caesium atomic clocks.
Nowm they might also become more compact and even portable, maybe in the future even travel to space.
PTB scientists have shown how some fundamental difficulties, which a more simple set-up had previously hindered, could be avoided.
They already have a practical application in mind: the clock could help to determine geographical heights even more exactly than before.
An optical clock is so exact because its “pendulum” swings so quickly.
The “pendulum” of a caesium atomic clock swings even more quickly: that is, that microwave radiation which can bring about a spin change in each electron of a caesium atom.
Precisely the microwave frequency at which this effect is largest defines the second. An optical atomic clock works with the still higher frequency of optical radiation - that is with an even faster pendulum.
As the movement of the atoms leads to very large frequency shifts through the Doppler effect, in the best of these clocks, the atoms are slowed down to a hundredth of the speed of a pedestrian in a first preparation step with the aid of laser cooling.
As the movement of the atoms leads to very large frequency shifts through the Doppler effect, in the best of these clocks the atoms are slowed down to a hundredth of the speed of a pedestrian in a first preparation step with the aid of laser cooling.
In a lattice clock, a further step then follows in which the atoms are held in potential wells.
These are created through the intensive light field of a laser. Several tens of thousands of strontium atoms are trapped in this so-called optical lattice.
The results of the investigation have shown how the optical lattice has to be dimensioned and how many atoms may be stored in it to operate a very accurate lattice clock also with strontium-88.
A clock is now being built on this basis that is more compact and more transportable than the previous lattice clocks.
First Published: Friday, September 04, 2009, 16:33