New record for the world’s most accurate clock

Time measurement has evolved to unprecedented precision with the advent of atomic clocks. Today, we are entering an even more precise era thanks to optical atomic clocks. These instruments far surpass the capabilities of traditional structures, promising considerable advances in various scientific and technological fields.

Atomic clocks: principle and usefulness

Atomic clocks, introduced in the 1950s, have revolutionized the measurement of time. They use cesium atoms cooled to temperatures close to absolute zero. The principle is based on measuring the resonance frequency of these atoms. Concretely, when a cesium atom passes from one energy level to another, it emits or absorbs electromagnetic radiation with a very precise frequency that serves as a reference for the oscillations of the clock. The most advanced atomic clocks lose less than a second in 300 million yearssufficient accuracy for many applications. One of the most common uses of these devices is the Global Positioning System (GPS). GPS satellites contain atomic clocks that synchronize their signals, allowing receivers on the ground to calculate their position with great precision. These machines are also crucial for telecommunications networks, the synchronization of financial transactions, and scientific research requiring precise time measurement.

Credits: Pitris/istock

A new precision record

Despite the impressive accuracy of traditional atomic clocks, scientists have sought to achieve even higher levels. optical atomic clocks represent this new generation. Using optical lattices, or “webs of light,” they trap and measure thousands of atoms simultaneously. A notable advance is the use of 40,000 strontium atoms cooled to a fraction of a degree above absolute zero. The energy transitions of these atoms provide an even more stable basis for measuring time. Recently, researchers have achieved astonishing precision with an uncertainty of only 8.1 parts per tenth of a billionth of a billionth. This precision far exceeds that of conventional atomic clocks and opens up new possibilities. For example, optical structures could improve the accuracy of GPS systems by a factor of a thousand, transforming navigation and mapping. This new generation of clocks could also play a key role in space exploration by enabling missions to be carried out with a precision never before achieved. Finally, the interest of these machines also goes well beyond these practical applications. Their extreme precision makes it possible to explore the foundations of physics, in particular Einstein’s general relativity. Optical atomic clocks can indeed detect tiny effects of the curvature of space-time, even at microscopic scales. This offers a unique opportunity to test physical theories with unprecedented rigor. Details of the study are published in Physical Review Letters.