Scientific experiments that want to redefine how long a second is
What is a second? One second? 60 parts of a minute? For more than sixty years what we understand per second has practically not changed. Although clocks accurately tick every second, this is often not sufficient for certain technologies or scientific experiments. Now a group of researchers claims to have a method 100 times more accurate than cesium atomic clocks, those used since 1960 to measure the time standard.
Atomic clocks are essential in many technologies to define precisely how some products and services work such as GPS. They are also used in scientific investigations to analyze components or measure distances. They have hardly any deviations and it takes millions of years for an atomic clock to drift one second forward or backward. Now, they can be more precise.
A group of researchers from the Boulder Atomic Clock Optical Network (BACON) in the United States has published a new study commenting on the experiments they have done to measure time more accurately. Using atomic clocks with atoms other than cesium and comparing their measurements they have been able to determine up to 100 times greater precision.
New atomic clocks, new standard
Atomic clocks use the frequency of a specific atomic transition as a stable time standard. As they explain, they compared three atomic clocks made with ytterbium atoms (we already saw how this allowed to have the most accurate atomic clock in the world), with strontium atoms and with a single electrically charged aluminum atom. These, in principle, allow higher frequencies than cesium atomic clocks, thus offering up to 100 times more precision.
Placing the clocks in different laboratories and with 1.5 kilometers of distance between them, they began to compare the measurements that gave. The information was sent by both an open-air laser link and a fiber optic link. With this they have been able to experience measurements up to 10 times more accurate than other watch comparisons.
So that? To achieve even smaller time measures and so have an even more precise standard than an exact second measures. In addition to improving the definition of the second, better comparisons of optical watches could benefit other branches of science. For example, they can serve to better understand how gravity affects time, to study dark matter or for things “as insignificant” as detecting changes in the Earth’s crust.
More information | Nature