Key facts
- Singapore's Centre for Quantum Technologies built the world's most accurate atomic clock.
- The clock uses a single ion of the rare earth metal lutetium.
- It is estimated to lose one second every 260 billion years.
- The clock is about four times more accurate than the previous record holder.
- The team reported an uncertainty of 1 x 10-19 for their lutetium clock.
- Two lutetium clocks were compared, agreeing to an uncertainty of 5.7 x 10-19.
A research team in Singapore has developed the world's most accurate atomic clock, surpassing previous records held by scientists in China and the United States. The clock, built using a single ion of the rare earth metal lutetium, is so precise that it would only lose one second over 260 billion years, a duration nearly 20 times the estimated age of the universe. This level of accuracy is approximately four times greater than the previous record holder, a calcium-ion clock developed by a Chinese Academy of Sciences team.
The clock's precision is based on measurements published in Nature on September 23, showing its superiority over clocks made from other elements. Team leader Murray Barrett, a Principal Investigator at Singapore's Centre for Quantum Technologies (CQT) and Associate Professor at the National University of Singapore, expressed confidence in the clock's accuracy. The researchers measured the frequency of their lutetium clock to 19 decimal places, achieving an uncertainty of 1 x 10-19, the lowest reported for any optical atomic clock to date. Furthermore, two identical lutetium clocks built by the team were compared over 200 hours, agreeing to an uncertainty of 5.7 x 10-19, which is the most precise clock comparison ever recorded.
Atomic clocks measure time by referencing an atomic transition, where an electron swaps energy levels. The frequency of this transition is a stable property of the atom, and a laser's oscillations are used to count time. While caesium atoms have been the global standard since the 1960s, scientists are exploring other elements like ytterbium, strontium, and aluminium for more accurate optical atomic clocks. The international body responsible for time standards is considering data from these new clocks for a potential redefinition of the second expected after 2030. The CQT team chose lutetium over a decade ago, believing it possessed ideal properties for top-tier timekeeping, and they are reportedly the only group currently working with this element for this purpose. Lutetium's clock transition is less affected by environmental factors like temperature and magnetic fields, contributing to its stability and high accuracy across diverse conditions.