Physicists at UCLA have taken a major step toward creating the most accurate clocks ever by using a thin film of thorium-229.
This new material could replace bulky crystals in atomic clocks and revolutionize how we measure time, gravity, and even the laws of physics.
Atomic clocks are the most precise tools for measuring time, relying on the oscillations of atoms to track seconds.
A new type of clock, based on thorium-229, excites the nucleus of the atom using a laser.
This process could lead to clocks far more accurate than today’s atomic clocks, offering insights into the universe’s fundamental forces.
However, thorium-229 crystals used for these clocks are both rare and radioactive, making them expensive and difficult to produce.
To solve this problem, UCLA researchers developed a thin film made from a precursor of thorium-229. This film requires much less material and is only as radioactive as a banana, making it safer and easier to produce.
The film also provides the same nuclear excitation needed for a thorium-based clock.
The team created the film by dissolving thorium-229 in ultrapure water, adding hydrogen fluoride, and then heating the resulting material. The thorium condensed onto transparent surfaces like sapphire, creating a stable film. When exposed to a vacuum ultraviolet laser, the film emitted photons, confirming the nuclear excitation needed for a nuclear clock.
Current atomic clocks are large, room-sized machines that require vacuum chambers and complex cooling systems. In contrast, a thorium-based clock using the new thin film would be much smaller, cheaper, and more portable. It could enable widespread use in everything from navigation to scientific research.
The thorium clock’s precision comes from its incredibly high tick rate—over 2 quadrillion cycles per second. The thin film ensures this tick rate remains stable, making the clock highly accurate.
Beyond practical uses, these new clocks could help scientists explore some of the biggest questions about the universe. Measuring the nucleus of an atom with such precision opens the door to discovering more about how matter and energy interact, potentially rewriting our understanding of physics.
“This thin film material is unique,” said Anastassia Alexandrova, a UCLA chemistry and materials science professor. “It offers a stable and accurate environment for creating the next generation of clocks.”
The development of thorium-based nuclear clocks could transform timekeeping and lead to groundbreaking discoveries in science, making this innovation a key step into the future.
