Atomic Physics and the World's Most Accurate Timekeeping

Greater understanding of atomic physics at the quantum level has led to the creation of our most accurate clocks—which in turn have made possible everything from satellite navigation to the internet.

For more than 60 years, the Office of Naval Research (ONR) has invested in atomic physics—the branch of physics concerned with the structure of the atom, its energy states, and its interactions with particles and fields. Basic research initially supported by ONR in the late 1970s on laser cooling and trapping of atoms and ions—which allow for experiments that observe quantum interactions at extremely low temperatures—led to the most accurate atomic clock devices ever made, which today serve as the primary time standards for both civilian and Department of Defense applications. The high accuracy of these clocks enables precise GPS navigation, the internet, wireless communications, and satellite-based sensors.

Two rubidium fountain clocks, part of the U.S. Naval Observatory Master Clock ensemble in Washington, D.C.Two rubidium fountain clocks, part of the U.S. Naval Observatory Master Clock ensemble in Washington, D.C.
(U.S. Navy photo)

In the words of Nobel Laureate William Phillips, speaking about the ONR investments leading to ultra-precise atomic clocks, “It was the long- term support of ONR, support that began when the ideas were vague and unproved, that made all of this possible. In my view, this represents the best aspects of the spirit that has made ONR the premier military research organization in the country (and therefore in the world).”

ONR continues to support the development of chip-scale atomic clocks, bringing orders of magnitude better timekeeping to handheld and other compact platforms at a fraction of the power. In the not-too-distant future, laser cooling and trapping techniques will likely produce the lowest noise inertial measurement sensors and the highest sensitivity, practical magnetic field sensors for biological imaging.

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