Press releases
Please quote Nature Photonics as the source of these items.
May 2007
Time set free
The phenomenal precision of optical clocks - the world's most accurate time-keepers - may be about to escape the confinement of the lab. A technique for transferring the accuracy of these clocks onto a beam of light compatible with the optical telecommunications networks that connect the world is reported in the May issue of Nature Photonics. This could allow the comparison of optical clocks in distant laboratories - vital if they are to be used to better define the second.
Optical clocks represent the ultimate in precision; they keep time by reference to a ray of light in which electric fields oscillate at about 100 trillion times every second. The result is a device that could remain accurate to within one second after a billion years. Clocks with such mind-boggling accuracy are at the very heart of global positioning systems (GPS) - improved timing means more precise positioning. But optical clocks are only truly valuable if they can be compared to one another to ensure accuracy.
Nathan Newbury and colleagues make use of state-of-the-art laser technology to transfer stable clock oscillations to a laser beam with a wavelength of 1.5 micrometers - the standard used by telecom networks. The ultra-precise signal was then transmitted over a 750-metre-long optical network, without significantly compromising its accuracy. The authors believe that the approach could be scaled up to transmission distances of 50 kilometres or more, demonstrating the potential for use in global telecommunication networks.
Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter
I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams & N. R. Newbury
Published online: 1 May 2007 | doi 10.1038/nphoton.2006.71