31/05/2023
Have a look at the NIST-F3 atomic fountain clock.
These sorts of clocks can get very close to the definition of the second, which is based on the image of a cesium atom completely isolated from the environment, existing in a universe all its own. That’s the ideal for measurement purposes.
But the cesium atoms in clocks on Earth exist in reality and under all of the environmental factors that come along with it. Ours reside in a vacuum chamber in Boulder, Colorado, so they behave slightly differently than the ideal definition of the second.
Experiments are ongoing to probe the small shifts that affect the atoms in NIST-F3. In the best fountain clocks, these shifts can be measured so accurately that the clock would not gain or lose a second in about 300 million years. We hope to achieve similar levels of stability in NIST-F3.
