There is a new, super-accurate clock ticking away in National Laboratory for Atomic, Molecular and Optical Physics (KL FAMO) in Poland. Although, it’s not really ticking because this is an optical atomic clock, one of only a few in the world. It’s so accurate that it would take billions of years to reach an error of one second. To put it another way, if you started an optical atomic clock at the moment of the big bang, it would have lost about one-tenth of a second by now. Now that’s something you can set your watch by.

The new Polish clock is no desktop timepiece. It occupies four rooms at KL FAMO and has three main components — an atomic standard, an optical comb, and an high-precision laser. Optical atomic clocks are still very new technology, but they have the potential to be even more accurate than the traditional cesium fountain clocks used for time-based experiments all over the world. In past tests of optical atomic clocks, researchers have found they had no trouble keeping time to the standards of the National Institute of Standards and Technology.

Researchers chose to use strontium 88 atoms as the atomic standard in this clock. Strontium 88 is the most common isotope of the alkaline earth metal, but radioactive strontium 87 can be used in one of the two standard containment chambers for increased accuracy. Strontium 88 is stable with a half-life measured in billions of years. The atoms are suspended in a vacuum at below 10 microkelvins. To record the passage of time with these atomic standard, you simply shoot a laser at them. Okay, it’s not that simple.

The laser emits light at a frequency of 429 terahertz, illuminating the atoms. The frequency of the laser is tuned to match the oscillations of the atomic standard. That frequency is far too high to count electronically, thus you can’t use it to keep time directly. That problem is bypassed with the optical comb. The optical frequency comb (another type of pulsing laser) is used to fire extremely short bursts of light that can be synchronized with the high-frequency main laser. It basically translates the unreadable high-precision laser into radio frequencies, which can then be counted electronically.

There are a lot of components to fine tune and things to test before the KL FAMO clock will be ready for use in experiments. You can’t just flip a switch and turn this clock into one of the most accurate timepieces on the planet. The early data collected from the clock indicate that it is already the most accurate clock in Poland, which has a number of conventional atomic clocks. having a highly-accurate way of tracking the passage of time is of vital importance when testing aspects of general relativity and particle physics.