Microcomb Chips Shrink Optical Atomic Clocks

Advancements in technology are paving the way for smaller atomic clocks that could revolutionize navigation, autonomous vehicles, and geo-data monitoring. Optical atomic clocks have the potential to significantly enhance the precision of time and geographic positioning in devices such as mobile phones, computers, and GPS systems. However, their current size and complexity limit their widespread adoption in society. A collaborative research effort between Purdue University in the USA and Chalmers University of Technology in Sweden has yielded a breakthrough technology utilizing on-chip microcombs to make ultra-precise optical atomic clock systems more compact and accessible.

When it comes to timekeeping devices, whether it's a mechanical clock, an atomic clock, or a smartwatch, they all consist of two fundamental components: an oscillator and a counter. The oscillator generates a regular frequency variation over time, while the counter tallies the oscillations. Atomic clocks, in particular, rely on measuring the oscillations of vibrating atoms transitioning between two energy states with remarkable precision.

Traditionally, most atomic clocks utilize microwave frequencies to drive these energy oscillations in atoms. However, recent advancements in the field have explored the use of lasers to optically induce these oscillations. Optical atomic clocks, akin to a ruler with an abundance of markings per centimeter, allow for the division of a second into even finer time intervals, resulting in vastly improved timekeeping and positioning accuracy.

The breakthrough technology at the heart of this innovation, detailed in a recent research publication in Nature Photonics, revolves around microcombs – small, chip-based devices capable of generating a spectrum of evenly distributed light frequencies. These microcombs play a crucial role in enabling the miniaturization of atomic clock systems while maintaining high precision.

While optical atomic clocks offer unparalleled precision, their oscillation frequencies typically operate in the hundreds of terahertz range – a frequency too high for conventional electronic circuits to directly process. The researchers' innovative use of microcomb chips has effectively addressed this challenge, allowing for a significant reduction in the size of atomic clock systems while preserving their accuracy and reliability.