RESEARCHERS have set a new record in the distance over which two atomic clocks can be synchronised via an optical fibre. Applications like GPS (Global Positioning System) navigation work by comparing timing signals coming from ultra-precise clocks at large distances. Such signals are normally relayed by satellite communication, but this cannot be done with the best available atomic clocks; they are so precise that small frequency shifts occurring during satellite transmission would be larger than the clock’s precision. Past experiments have shown that optical fibre links on the ground can replace satellites, by faithfully transmitting clock frequencies over hundreds of kilometres. Now, researchers at the Max-Planck-Institute of Quantum Optics in Germany have doubled the previous distance record, connecting two clocks over a distance of 1,840 km via a dedicated optical fibre between two German research centres. The method may one day link together optical clocks around the world. The work has been published in the latest issue of Physical Review Letters.
Cross-country time-keeping
A letter from the Editor
Dear reader,
The COVID-19-induced lockdown and the absolute necessity for human beings to maintain a physical distance from one another in order to contain the pandemic has changed our lives in unimaginable ways. The print medium all over the world is no exception.
As the distribution of printed copies is unlikely to resume any time soon, Frontline will come to you only through the digital platform until the return of normality. The resources needed to keep up the good work that Frontline has been doing for the past 35 years and more are immense. It is a long journey indeed. Readers who have been part of this journey are our source of strength.
Subscribing to the online edition, I am confident, will make it mutually beneficial.
Sincerely,
R. Vijaya Sankar
Editor, Frontline
Oh to be a scientist!
New bile acids discovered
High demand for Li-ion batteries can affect cobalt supply
Microbes deep beneath the ocean floor
Bt cotton no match for Indian pests
Birdsong can tell bird size
Please Email the Editor