Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Atomic clock signals may be best shared by fiber-optics

06.03.2007
Time and frequency information can be transferred between laboratories or to other users in several ways, often using the Global Positioning System (GPS).

But today's best atomic clocks are so accurate—neither gaining nor losing one second in as long as 400 million years—that more stable methods are needed. The best solution may be to use lasers to transfer data over fiber-optic cables, according to scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

The use of fiber-optic channels to transfer time signals allows accurate comparisons of distantly located atomic clocks of different types. This could lead, for example, to enhanced measurement accuracy in experiments to determine whether so-called "constants of nature" are in fact changing. Sharing of clock signals via fiber also will enable synchronization of components for advanced X-ray sources at linear accelerators, which may power studies of ultrafast phenomena in chemistry, biology, physics and materials science; or link arrays of geographically distributed radio telescopes to produce the power of a giant telescope.

Three state-of-the-art techniques for distributing ultra-stable time and frequency signals over fiber are described in a new review article* by NIST Fellow Jun Ye's group at JILA. Fibers can be far more stable, especially when efforts are made to cancel molecules along the transmission path, than the paths through free-space used by GPS, which requires days of measurement averaging to accurately compare today's best frequency standards. Moreover, considerable fiber-optic infrastructure already exists. For instance, the new paper is based largely on research performed on a 3.45-km fiber link installed in underground conduits and steam tunnels between JILA and NIST laboratories in Boulder.

Microwave frequency signals such as from NIST's standard atomic clock www.nist.gov/public_affairs/techbeat/tb2005_0923.htm#clock can be distributed over fiber using a continuous-wave (cw) laser. Another method can transfer more accurate optical frequency references such as NIST's mercury ion clock www.nist.gov/public_affairs/releases/mercury_atomic_clock.htm or JILA's strontium clock with a cw laser and disseminate signals to both optical and microwave users using an optical frequency comb www.nist.gov/public_affairs/newsfromnist_frequency_combs.htm. As a third option, microwave and optical frequency references can be transmitted simultaneously using a frequency comb.

Noting that gravitational effects may eventually limit ground-based atomic clocks, the paper suggests someday creating a network of optical atomic clocks in space, which might be used to make flawless distance measurements, transfer clock signals to different locations, and accurately map the Earth's gravity distribution.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Information Technology:

nachricht Seeing the forest through the trees with a new LiDAR system
28.06.2017 | The Optical Society

nachricht Drones that drive
27.06.2017 | Massachusetts Institute of Technology, CSAIL

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

New photoacoustic technique detects gases at parts-per-quadrillion level

28.06.2017 | Physics and Astronomy

Funding of Collaborative Research Center developing nanomaterials for cancer immunotherapy extended

28.06.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>