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Time & frequency

Overview

Time and frequency activities at NIST include maintaining standards, providing official time to the U.S., and carrying out a broad program of research and service activities in time and frequency metrology.

The Research

Projects & Programs

Compact Cold Atom Instruments

Ongoing
The cooling of atoms to microkelvin temperatures using lasers is currently enabling a new generation of precision instruments that take advantage of the long

Calcium Thermal Beam Optical Clock

Ongoing
A simple, compact alternative to the highest performing optical standards, the Ca clock uses a thermal beam of neutral atoms with one or two lasers to achieve

Frequency Comb Spectroscopy

Ongoing
We use frequency combs based on ultrafast mode-locked lasers to perform precision spectroscopy in the near- and mid-infrared domains, for rapid, high

Additional Resources Links

What Is Time?

Philosophically, what is "time"? Even if we don’t completely understand what time is, we can precisely measure what time it is, thanks to the atomic clock, humankind’s most accurate measurement device. Atomic clocks have revolutionized navigation. Only time will tell us its future applications.

What is time?
What is time?

News

NIST physicist Elizabeth Donley and Compact Atomic Clock

Keeping Time at NIST

Einstein is reported to have once said that time is what a clock measures. Some say that what we experience as time is really our experience of the phenomenon of entropy, the second law of thermodynamics. Entropy, loosely explained, is the tendency for things to become disorganized. Hot coffee always goes cold. It never reheats itself. Eggs don’t unscramble themselves. Your room gets messy and you
Adam Kaufman poses for a head shot with a shelf of library books in the background.

NIST Physicist Adam Kaufman Wins Breakthrough New Horizons in Physics Prize

A globe spins on a curved stand, blurring the shape of North America.

Spotlight: Keeping Time With the Earth’s Rotation

A woman with a ponytail sits next to a rack of electronics, adjusting wiring.

Spotlight: Using PEACOCS to Link Atomic Time Signals Across Longer Distances