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Last Updated: Wednesday, 25 February, 2004, 18:53 GMT
Shortest time interval measured
Clock, BBC
New developments are producing to ever more accurate time technologies
Scientists claim they have measured the shortest interval of time ever.

Researchers used short pulses of laser light to produce images of electrons leaving atoms and recorded what happened to within 100 attoseconds.

To imagine how long this is, if 100 attoseconds is stretched so that it lasts one second, one second would last 300 million years on the same scale.

Scientists used the technique to record the dynamics of electrons in atoms and report their findings in Nature.

The research team employed extreme ultraviolet (XUV) light pulses to excite atoms, prompting them to emit electrons, the small negatively charged particles that are a fundamental part of every atom.

"We accelerate the electrons spinning around the nucleus. Some pick up so much energy that they leave the atoms forever," Professor Ferenc Krausz, of the Technische Universitat Wien, in Austria, told BBC News Online.

Future clocks

At the same time, the scientists used a device called a Few-Cycle Laser to capture "tomographic images" of these electrons that gave information about how they behaved with time.

This allowed the scientists to distinguish events within 100 attoseconds, the shortest interval of time ever recorded.

An attosecond is one quintillionth (10 to the power of minus 18) of a second
Caesium atomic clocks are accurate to one second over many millions of years
The development of laser counters will push clocks to theoretical billion-year accuracy
The clocks' technology will be used in telecommunications and experiments testing fundamental theories in physics
They will also be used to time important processes in biologocal cells, to aid our understanding of disease
The advance opens up the possibility of more accurate timekeeping.

Existing atomic clocks are very accurate and measure time by counting the number of times caesium atoms jump back and forth between different energy levels.

These jumps, or "ticks", occur at microwave frequencies. But researchers are increasingly looking to count ticks using optical frequencies, with the help of lasers.

This would offer the prospect of more stable and therefore more accurate clocks.

"The more stable the clock, the better you can measure time," said Dale Henderson of the UK's National Physical Laboratory.

No time left to lose
15 Feb 03  |  Denver 2003
World's most precise clock developed
12 Jul 01  |  Science/Nature

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