Scientists Develop Ultra-Precise Atomic Clock Potentially Redefining the Second

Scientists at Singapore's Centre for Quantum Technologies (CQT) have developed what they claim is the world's most accurate atomic clock, a device so precise it could redefine the fundamental unit of time, the second. The clock measures time to 19 decimal places, an accuracy level that would cause it to lose only one second over more than 260 billion years. The researchers reported this uncertainty of 1 x 10–19 in the journal Nature.

The new clock utilizes the element lutetium, a choice made based on the element's unique properties that make its atomic transitions less susceptible to environmental factors like temperature and magnetic fields. These stable properties allow for high accuracy across a wide range of conditions, according to team leader Murray Barrett from the National University of Singapore. "In the future, I just don't see how this clock can be beat," Barrett stated.

Atomic clocks function by monitoring the precise frequency of an atomic transition, typically when an atom's electron changes energy levels. Lasers are tuned to these transitions, and the light oscillations are used to count time. While cesium atoms have historically set the standard for timekeeping since the 1960s and support critical systems like GPS, elements such as ytterbium, strontium, and now lutetium, oscillate at much higher frequencies, enabling greater accuracy.

The CQT team verified their lutetium clock's accuracy by comparing two such devices, finding their ticks matched to the 19th digit, which they state is the most precise clock comparison ever conducted. The researchers noted that comparing this new clock to existing ultra-precise atomic clocks is challenging because such devices are sensitive enough to detect gravitational time dilation differences over mere millimeters of height, and Earth's gravitational field variations are not yet known with sufficient precision for such comparisons.

The next phase for the research involves miniaturizing the lab-scale clock into a transportable system without compromising its accuracy. This development could open doors for new applications. Beyond enhanced timekeeping, these advanced clocks have the potential to aid in probing fundamental physics questions, detecting minute gravitational changes, and contributing to a redefinition of the second. The international body responsible for time standards is expected to consider data from new optical atomic clocks for a potential redefinition of the second in or after 2030. This lutetium clock's independently verified accuracy at the 19th decimal place marks a significant advancement, building on previous records set by other optical clocks.