Posted by Richard N Williams on April 6th, 2011
A new atomic clock as accurate as any produced has been developed by the University of Tokyo which is so accurate it can measure differences in Earth’s gravitational field—reports the journal Nature Photonics.
While atomic clocks are highly accurate, and are used to define the international timescale UTC (Coordinated Universal Time), which many computer networks rely on to synchronise their NTP servers to, they are finite in their accuracy.
Atomic clock use the oscillations of atoms emitted during the change between two energy states, but currently they are limited by the Dick effect, where noise and interference generated by the lasers used to read the frequency of the clock, gradually affect the time.
The new optical lattice clocks, developed by Professor Hidetoshi Katori and his team at the University of Tokyo, get around this problem by trapping the oscillating atoms in an optical lattice produced by a laser field. This makes the clock extremely stable, and incredibly accurate.
Indeed the clock is so accurate Professor Katori and his team suggest that not only could it man future GPS systems become accurate to within a couple of inches, but can also measure the difference in the gravitation of the Earth.
As discovered by Einstein in his Special and General Theories of Relativity, time is affected by the strength of gravitational fields. The stronger the gravity of a body, the more time and space is bent, slowing down time.
Professor Katori and his team suggest that this means their clocks could be used to find oil deposits below the Earth, as oil is a lower density, and therefore has a weaker gravity than rock.
Despite the Dick Effect, traditional atomic clocks currently used to govern UTC and to synchronise computer networks via NTP time servers, are still highly accurate and will not drift by a second in over 100,000 years, still accurate enough for the majority of precise time requirements.
However, a century ago the most accurate clock available was an electronic quartz clock that would drift by a second a day, but as technology developed more and more accurate time pieces were required, so in the future, it is highly possible that these new generation of atomic clocks will be the norm.