A research group consisting of Yokohama National University and Takumi Kobayashi, a researcher at the Industrial Technology Research Institute, has jointly developed an ytterbium optical lattice clock that can be operated for a long time.It is expected to contribute to improving the accuracy of the International Atomic Time in the future.
The unit of time, "second," is currently defined using the frequency of microwaves that resonate with transitions between certain levels of cesium atoms, but in recent years, more accurate optical grid clocks (atoms that use light). Clock) is attracting attention.In addition, at a recent conference related to the Meter Convention, one of the conditions such as the required accuracy for redefining seconds was to improve the accuracy of the International Atomic Time by using an optical clock.Currently, research on strontium optical lattice clocks is taking the lead as optical clocks that can be operated for a long period of time, but ytterbium optical lattice clocks, which have many advantages in terms of high accuracy, are also being developed all over the world.
Since an optical lattice clock is a complicated device that uses a large number of laser light sources, it is necessary to precisely control all laser frequencies in order to operate the clock.This time, the research group has built a new system that controls all laser light sources with an "optical frequency comb" (light with a wide-band comb-shaped (comb) spectrum output from an ultrashort light pulsed laser). The stable operation of the frequency comb optical grid clock has been realized.
When the developed ytterbium optical lattice clock was operated regularly within a few months of the experimental period, the cumulative operating time was 60 hours or more, indicating that it has the ability to contribute to improving the accuracy of the International Atomic Time in the future.Moreover, when the error evaluation was performed, it was confirmed that the relative error of the frequency was about 9000 second in 1 million years.
In the future, it aims to further improve the stability and reliability of the Ytterbium optical lattice clock, improve its perfection as a standard, and contribute to the International Atomic Time.
Paper information:[IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control] Uncertainty evaluation of an 171Yb optical lattice clock at NMIJ.
