The world's first nuclear clocks: extreme precision

Two independent teams of scientists, one in Vienna and the other in Beijing, have developed the world's first nuclear clocks. These devices represent the new generation of atomic clocks and are based on the thorium-229 isotope enclosed in calcium fluoride crystals.

Their operation relies on the interaction between ultraviolet light emitted by a high-power laser and the thorium-229 nucleus. Subatomic particles within the nucleus repeatedly transition from one energy level to another, and the precise counting of these oscillations yields the measurement of time. Both nuclear clocks lose just one second every million years.

Despite this achievement, researchers emphasize that we are still far from the extreme precision of traditional atomic clocks, which can operate without errors for billions of years. Potential applications include satellite navigation and data transfer synchronization.

Nuclear clocks represent the evolution of atomic clocks, devices first created in 1949 that measured time based on the energy oscillations of electrons. For decades, physicists have sought to develop an even more precise technology, leveraging the properties of atomic nuclei instead of electrons.

Research on nuclear clocks began seriously in 2008, when the team at the Technical University of Vienna started working on the project. The breakthrough came after twenty years of research, when physicists finally managed to identify the exact resonance frequency of thorium-229, with a wavelength of 148 nanometers in the ultraviolet spectrum.

Thorium-229 was chosen because it is a rare isotope capable of changing its energy state in a controllable manner. The two teams developed completely different experimental approaches: Vienna has better crystals with a higher concentration of thorium, while Beijing possesses more powerful lasers. In the future, by combining these resources, even more efficient devices could be created.