(Image credit: Kai Wu)
A new comb-shaped computer chip could provide drones, smartphones and autonomous vehicles with military-grade positioning technology previously reserved for space agencies and research labs.
Scientists have unveiled a “microchip comb” – a 5-millimeter-wide (0.2-inch) computer chip with tiny comb-like teeth that could make optical atomic clocks, the most accurate timekeeping devices on the planet, small and practical enough for real-world use.
This could mean GPS systems that are a thousand times more accurate than the best we have today, improving everything from navigation for smartphones and drones to seismic monitoring and geological surveys, the researchers said in a press release. They published their findings Feb. 19 in the journal Nature Photonics.
Up and Atom
“Modern atomic clocks allow GPS systems to determine locations with an accuracy of a few meters [1 meter equals 3.3 feet]. With optical atomic clocks, we can achieve an accuracy of just a few centimeters [where 1 centimeter equals 0.4 inches],” said study co-author Minghao Qi, a professor of electrical and computer engineering at Purdue University.
“This increases the autonomy of vehicles and all electronic systems that depend on positioning. Optical atomic clocks are also capable of detecting small changes in latitude on the Earth's surface and can be used to monitor, for example, volcanic activity.”
There are about 400 high-precision atomic clocks in the world that use the principles of quantum mechanics to measure time.
Typically, this involves using microwaves to excite atoms into transitions between energy states. These transitions, called oscillations, occur naturally at incredibly high speeds, acting like a super-precise ticking clock that maintains accurate timekeeping to within a billionth of a second.
That's why atomic clocks form the basis of Coordinated Universal Time (UTC), which is used to set the world's time zones, and GPS (Global Positioning System) satellites, which rely on atomic time to provide location data to cars, smartphones, and other devices.
Despite this amazing accuracy, traditional atomic clocks are significantly less accurate than optical ones. While standard atomic clocks use microwave frequencies to excite atoms, optical atomic clocks use laser light, which allows them to measure atomic vibrations at a much finer level — making them thousands of times more accurate.
Until recently, optical atomic clocks were only available at very limited scientific and research facilities, such as NASA's Goddard Space Flight Center and the National Institute of Standards and Technology (NIST). This is due to their complexity, which makes them inaccessible to the average user.
Tapping the teeth of a comb
Microcomb microchips could change that by bridging the gap between the high-frequency optical signals (which optical atomic clocks use) and the radio frequencies needed for the navigation and communication systems that power modern electronics.
“Like the teeth of a comb, a microcomb consists of a spectrum of uniformly distributed light frequencies. An optical atomic clock can be constructed by coupling a microcomb tooth to an ultra-narrow linewidth laser, which in turn couples to an atomic transition with exceptionally high frequency stability,” the researchers explained in a statement.
They likened the new system to a set of gears, where a small, fast-spinning gear (optical frequency) drives a larger, slower one (radio frequency). Just as gears transmit motion by reducing speed, the microcell functions as a transducer, converting the ultrafast vibrations of atoms into a stable time signal that electronics can process.
“Moreover, the compact size of the microcell allows the atomic clock system to be significantly reduced while maintaining its exceptional accuracy,” the co-author noted.
Sourse: www.livescience.com
