Physicists Have Created The Basis For Ultra-Precise Atomic Clocks
European and Russian scientists have created and tested a technique that allows you to track the position of electrons in the vicinity of highly charged ions. This discovery will create a super-accurate atomic clock, scientists write in the scientific journal Nature.
"Such watches made based on highly charged ions will be especially interesting for science. In particular, their accuracy for the first time will allow physicists to conduct experiments to search for the lightest forms of dark matter, traces of new physics in variations of the values of fundamental constants, and also to test the theory of relativity once again," commented Marianna Safronova, a physicist from Delaware University (USA).
An atomic clock is an ultra-precise system for measuring time. The pendulum in it is ytterbium ions or some other chemical elements with special physical properties. They are located inside special electromagnetic traps and are cooled to temperatures close to absolute zero.
The algorithm that controls the operation of the atomic clock periodically irradiates these ions with a special laser beam, causing their external electrons to oscillate between different energy levels. Atoms of the same type "switch" between these States at the same time and with the same frequency, which allows you to track the passage of time very accurately.
The creation of such a clock almost a decade ago allowed physicists to increase the accuracy of time measurement by several orders of magnitude. However, such a device is still vulnerable to various external interference. Most of these problems, as scientists have long known, can be solved with the help of so-called highly charged ions-atoms that are devoid of not one or two, but several dozen electrons.
The problem, as scientists from the St. Petersburg Institute of nuclear physics in Gatchina, as well as their foreign colleagues, write, is that physicists did not have accurate ideas about how energy levels are arranged and how electrons rotating around such ions behave. Similarly, their properties cannot be calculated by theoretical methods with an accuracy that would be sufficient for the operation of an atomic clock.
Experts solved this problem by drawing attention to a pattern inspired by Einstein's theory of relativity. According to its calculations, the mass and it should change somewhat if one of its electrons moves from a state of rest to higher energy levels. This allows us to study the structure of these levels and how different transitions are suitable for creating an atomic clock, without destroying the ion itself.
Guided by this idea, the authors of the article made the first measurements of this kind for highly charged rhenium ions, one of the rarest elements on Earth. To do this, scientists stripped rhenium atoms of 29 electrons at once and placed them in a special "matryoshka" of five nested traps, whose electromagnetic fields caused the ions to move along a circular wavy line. Any changes in their mass changed the nature of the movement of ions inside the trap, which allowed scientists to measure these shifts very accurately.
This technique allowed physicists to study in detail the structure of energy levels in rhenium ions and take a big step towards creating ultra-precise atomic clocks based on such particles. Rhenium itself can not be used to create such devices, but this technique, as scientists conclude, can be used to study the properties of ions of other elements suitable for this role.