Researchers at the University of Science and Technology of China have allegedly built an optical clock with stability and uncertainty of under five quintillionths. The clock will lose or gain one second in the next seven billion years. It is, therefore, likely to depict accurate time throughout our lifetimes.
Optical clocks have a critical role in the future that is shaping up today. Scientists are confident they can develop more accurate global positioning systems (GPS) and quantum key distribution using optical clocks.
Research teams from Japan, the US, and Germany have been working on developing atomic clocks. However, the most precise atomic clock is hosted at the University of Colorado in Boulder and is also stable in its operation. With their recent achievement, China has become the second nation in the world to have demonstrated precise timekeeping. However, the clock needs to be more accurate than its US counterpart.
What is a second?
A second, which might seem like a little tick on a clock, is defined by science based on an atomic clock, known as a microwave fountain clock. The clock releases cesium atoms upwards, which fall back toward the Earth due to gravity, much like water flows in a fountain. The atoms are then excited with microwave pulses, which causes electrons to absorb and emit light particles and jump to different energy levels.
Each such cycle is a small tick that makes up fractions of a second, allowing scientists to maintain precise timekeeping down to several quadrillionths. However, the precision of such a clock depends on the microwave frequency. Therefore, researchers have been developing an optical clock that replaces the microwave with laser light. This is estimated to improve the clock’s performance by two orders of magnitude.
Building optical clocks for the future
We require at least three laboratories to achieve stability below five quintillionths and uncertainty below two quintillionths to adopt optical digital clocks. Under the guidance of Pan Jianwei, the Chinese research team used strontium to make their optical clock.
The researchers cooled down strontium atoms to temperatures of a few micro-Kelvin. Then, they trapped them in a one-dimensional lattice created with the help of intersecting laser beams. They then used an ultra-stable laser to trigger the atoms and bring about a clock transition that was stable and precise.
Comparisons with other independent clocks confirmed that the optical clock was stable to 2.2 quintillionths while its uncertainty was 4.4 quintillionths. In Metrologia’s research journal, the researchers said their optical clock would lose or gain one second in 7.2 billion years.
This puts the team’s effort in the minimum criteria required toward building a future that uses optical clocks for precise timekeeping. The researchers also plan to use other atoms, such as ytterbium, to make the clock and compare differences in the timekeeping.
Source: IE
