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Spotlight: Ultraprecise Time Signals Travel Across 28 Kilometers

A small pickup truck and trailer stand on a grassy slope with snow and mountains in the background.
Credit: M. Bodine/NIST

Timekeeping slippin’ into the future: For the first time, a NIST team transferred ultraprecise time signals over 28 kilometers of turbulent airspace (the longest range yet for eye-safe laser light!) by way of a signal relay point in the field.

Imagine a triangular section of land and sky, with three points (or nodes) bouncing signals off of each other. Researchers sheltered one of the nodes inside the uninsulated wooden trailer shown here at the NOAA Table Mountain Test Facility in Longmont, Colorado. The others resided in a NIST lab facility 14 kilometers away.

The network’s performance during the experiment was stable enough to support state-of-the-art atomic clocks, a step toward future airborne or space-borne clock networks and maybe even the redefinition of time or the search for mysterious dark matter.

Find the full details on this advance in timekeeping in APL Photonics.

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Released August 3, 2020, Updated April 26, 2021