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Scientists create new atomic clock that is both ultra-precise and sturdy

By Peter Fitzgibbon - 29th April 2024 - 13:29

A team of physicists and engineers at Vector Atomic, Inc., a maker of navigation and communications equipment, has developed a new kind of atomic clock that they claim is both ultra-precise and sturdy. In their paper published in the journal Nature, the group describes the factors that went into building their new clock and how well it has worked during field tests aboard a ship in the Pacific Ocean.

New Atomic Clock lead
The 3 U, 19-inch rackmount iodine optical clock occupies a volume of 35 l and consumes less than 100 W.

Bonnie Marlow and Jonathan Hirschauer, both with the MITRE Corporation, have published a News & Views piece in the same journal issue, outlining the need for ultra-precise atomic clocks and the work done by the team at Vector Atomic.

As the tools used aboard ships have grown more sophisticated, the technology behind them has become increasingly reliant on precise timing. Navigation uses radio systems, for example, that use GPS. With such systems, very small time inaccuracies when measuring signal propagation between satellites can result in positioning errors of hundreds of meters, which can matter a lot when military vessels are involved.

Ships currently rely on atomic clocks that are robust enough to be able to work while on a rolling vessel, but they are not nearly as accurate as the atomic clocks used in research labs. In this new effort, the team at Vector Atomic has developed a clock to help bridge the difference.

The clock is based on the use of oscillating iodine molecules and weighs just 26 kilograms, which is about the size of three shoeboxes—small enough for use on virtually any ship. The group claims that it is approximately 1,000 times more precise than the types of clocks currently in use on most ships.

In developing the clock, the team has been working with New Zealand's navy. They tested the clock aboard the HMNZS Aotearoa as it conducted normal shipping operations for three weeks in the Pacific Ocean. Data from the tests showed that the clock was nearly as accurate as it was when tested in the lab—it kept time to within 300 trillionths of a second over any given day.

New Atomic Clock 3a
a, Clock stackup for RIMPAC 2022. The server rack contained three independent optical clocks, a 1 U power supply and control laptop for each clock, an uninterruptable power supply and the measurement system in a total rack volume of 23 U. b, The cargo container housing the clocks was craned onto the deck of the HMNZS Aotearoa, where it remained for the three-week naval exercise. c, A GPS track of the Aotearoa’s voyage around the Hawaiian Islands. The ship started and ended its voyage at Pearl Harbor, O’ahu.
New Atomic Clock 1
a, Measured phase noise for the iodine clock at 10 MHz, 100 MHz and 1,064 nm. b, Overlapping Allan deviation for the iodine clock operating at NIST and at sea. At short timescales, the instability in a dynamic environment is identical to the laboratory. The iodine clock can maintain less than 10−14 frequency instability for several days despite several-degree temperature swings, significant changes in relative humidity and changing magnetic fields. c, The clocks can maintain holdovers of 10 ps for several hours and 1 ns for several days, showing their potential as the basis for a picosecond-level timing network.

The development team notes that they are continuing to work on the clock, hoping to make it small enough to carry aboard navigation satellites.

More information: Jonathan D. Roslund et al, Optical clocks at sea, Nature (2024). DOI: 10.1038/s41586-024-07225-2

Bonnie L. S. Marlow et al, Robust optical clocks promise stable timing in a portable package, Nature (2024). DOI: 10.1038/d41586-024-01022-7

Journal information: Nature

Read More: Satellite Positioning, Navigation & Timing (PNT) Marine Navigation

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