Researchers from the National Institute of Standards and Technology (NIST) have successfully demonstrated an experimental atomic clock. This next-generation atomic clock operates at much smaller frequencies and is made up of just three chips in addition to supporting electronics and optics. Scientists believe their new design could have future use in a variety of different applications.
The clock, which is chip-sized, runs on the vibrations of rubidium atoms. The atoms are contained in a vapor cell on-chip, which is made up of a tiny glass container. The chips contain two frequency combs, which operate as gears that can link the atoms’ high-frequency vibrations, or ticks, to the more commonly used lower microwave frequencies.
The focal point of the new clock, which is chip-based, operates on very little power. It requires about 275 milliwatts to function. Scientists believe that additional technological advances could reduce its diminutive size even further.
“We made an optical atomic clock in which all key components are microfabricated and work together to produce an exceptionally stable output. Ultimately, we expect this work to lead to small, low-power clocks that are exceptionally stable and will bring a new generation of accurate timing to portable, battery-operated devices.”
The vibrations of the rubidium atoms are at an optical frequency found in the terahertz band. Scientists use the vibrations in order to stabilize the infrared laser in the clock. The laser is then converted to a gigahertz microwave clock signal by the two frequency combs attached to the chips. One comb operates at a terahertz frequency and has a broad enough range that it is capable of stabilizing itself. The two combs synchronize together, operating as a ruler that is finely spaced and locked to the clock laser. This allows the clock to create a gigahertz microwave electrical signal that is capable of being measured with conventional electronics. Additionally, this also serves to stabilize the vibrations of the rubidium atoms.
Researchers are hopeful that chip-scale optical clocks of this nature could one day replace traditional oscillators in telecommunication networks and navigation systems, and could even operate as backup clocks on satellites. Scientists will next work to improve the stability of the chip-based clock with low-noise lasers. They also hope to further reduce the size of the device.
