This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Take a second and turn it into trillions of moments. That's how precisely an atomic clock at Singapore's Centre for Quantum Technologies (CQT) keeps time—and with record-setting accuracy, according to results published in Nature on Sept. 23.
"I am confident that what we have now is the most accurate clock in the world," says team leader Murray Barrett, a CQT principal investigator and associate professor in the Department of Physics at the National University of Singapore. The researchers base their claim on measurements showing that their atomic clock, built from the element lutetium, outperforms previous record holders built from different elements. More accurate clocks hold promise for probing unknowns in fundamental physics and monitoring gravitational changes across Earth—and they are vying to redefine the second.
Atomic clocks keep time by referring to an atomic transition, when one of an atom's electrons changes energy levels. The frequency of this transition is a fixed property of the atom. A laser is matched to this "clock transition," and the light oscillations act like a pendulum to count time.
The basic method has been in place for decades. Cesium atoms have set the global standard for time since the 1960s, and cesium atomic clocks already support the Global Positioning System (GPS) and synchronize communication and transport networks. But scientists have been pushing the limits of timekeeping with other elements.
Elements such as recent record holders ytterbium, strontium and aluminum oscillate much faster than cesium, helping them keep time more accurately. The international body responsible for time standards is considering data from such new optical atomic clocks toward a redefinition of the second expected in or after 2030. The CQT team started working with lutetium over a decade ago on the hunch that it had the right properties to join the set of top-performing clocks.
To its knowledge, it is the only group working with this element for timekeeping so far. Now, the team has measured the frequency of its lutetium clock to 19 decimal places, reporting an uncertainty of 1 x 10-19, the lowest reported for any optical atomic clock to date. The researchers also built two clocks and compared their ticking.
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