From antiquity, we, human beings, started to explore getting more accurate "time" through the cosmic observation such as the sun and the moon. By early this century, the accuracy of "cesium atomic clocks" achieved one second cumulative error over several ten millions of years. Such atomic clocks have become the basic technology to sustain our globalized daily activities. For example, they are utilized for today's globalscale highspeed broadband telecommunication networks and the worldwide navigation system through GPS (Global Positioning System).
This research project aims to develop accurate clocks that surpass cesium atomic clocks, i.e., the current definition of "a second". The research director, Hidetoshi Katori had invented an "optical lattice clock". This clock determines the precise "atomic second" by measuring frequency of laser light absorbed by millions of ultracold atoms trapped in an optical lattice. The research project implements sophisticated laser cooling, quantum control, and stateoftheart laserstabilization technologies to develop "optical lattice clocks" targeting 18 digits of precision. This accuracy is equivalent to less than one second error over 13.7 billion years since the Big Bang, the birth of the universe.
The realization of the "optical lattice clocks" will allow reading out the curved "spacetime" due to the earth gravitational field at our personal scale and in the time scale of seconds. In this sense, our research revolutionizes the traditional time measurement and the concept of sharing the "time". Such clocks will find new applications in geodetic measurements, to be called "relativistic geodesy". The project also plans to explore applications, such as in surface sciences and quantum computing by applying the optical lattice clock technique.
