Researchers Develop Breakthrough In Timekeeping

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Researchers have developed a new method that may help them to measure time with unprecedented accuracy, a discovery that could have ramifications for spacecraft navigation, broadband data and other physics, and technological applications.

A team of physicists from the United States and Russia--including those from the National Institute of Standards and Technology (NIST)--have developed a way to compute a tiny, temperature-dependent source of error in atomic clocks.

It's a small correction, but paves the way toward a longstanding goal to develop a clock with a precision equivalent to one second of error every 32 billion years-longer than the age of the universe, according to NIST.

Various technologies and areas of scientific research are dependent on computing time as precisely as possible. Synchronizing broadband data streams, for instance, requires accurate timing in order to provide optimum quality of service.

Researchers came up with the method of correction by studying heat radiation, according to NIST. Any object at any temperature emanates this kind of radiation, including what researchers analyzed for their work--a hypothetical perfect radiant heat source known as a "black body.

Because even isolated atoms can sense the temperature of their environment, researchers were able to observe how so-called black body radiation, or BBR, enlarges the size of electron clouds within an atom by one part in a hundred trillion. The size is a major challenge to precision measurement, according to NIST, and researchers aimed to correct for this shift.

To do this, the research team used quantum theory of atomic structure to calculate the shift of the atomic energy levels of the aluminum ion. To be sure of their method, they reproduced the energy levels of the ion, and also compared their results against a predicted BBR shift in a strontium ion clock that was recently constructed in the United Kingdom.

In the end, their calculations reduced uncertainty due to room-temperature BBR in the aluminum iron to a factor of seven better than any previous calculations.

While the current aluminum-ion clocks have larger sources of uncertainty than what researchers observed, researchers should be able to use the benefits of the discovery to reduce large uncertainties in next-generation versions of them, according to NIST.

"We hope that our work will further improve upon what is already the most accurate measurement in science: the frequency of the aluminum quantum-logic clock," said Charles Clark, a physicist at the Joint Quantum Institute who co-authored the paper publishing the research, according to a press statement. The institute is a collaboration of NIST and the University of Maryland.