Microcomb chips can shrink optical atomic clock and create more accurate GPS systems
Smaller atomic clocks will be used for navigation, autonomous vehicles and geo-data monitoring
Optical atomic clocks can increase the precision of time and geographic position a thousandfold in our mobile phones, computers, and GPS systems. However, they are currently too large and complex to be widely used in society. Now, a research team from Purdue University, USA, and Chalmers University of Technology, Sweden, has developed a technology that, with the help of on-chip microcombs, could make ultra-precise optical atomic clock systems significantly smaller and more accessible.
All sorts of clocks – be it mechanical, atomic or a smartwatch – are made of two parts: an oscillator and a counter. The oscillator provides a periodic variation of some known frequency over time while the counter counts the number of cycles of the oscillator. Atomic clocks count the oscillations of vibrating atoms that switch between two energy states with very precise frequency.
Most atomic clocks use microwave frequencies to induce these energy oscillations in atoms. In recent years, researchers in the field have explored the possibility of using laser instead to induce oscillations optically. Just like a ruler with a great number of ticks per centimeter, optical atomic clocks make it possible to divide a second into even more time fractions, resulting in thousands of times more accurate time and position indications.
The core of the new technology, described in a recently published research article in Nature Photonics, are small, chip-based devices called microcombs. Like the teeth of a comb, microcombs can generate a spectrum of evenly distributed light frequencies.
While the optical atomic clocks offer much higher precision, the oscillation frequency is at hundreds of THz range – a frequency too high for any electronic circuits to “count” directly. But the researchers’ microcomb chips were able to solve the problem – while enabling the atomic clock system to shrink considerably … more
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