Experiments have been conducted "to bring out an ultrahigh precision atomic clock outside the laboratory and measure the difference in elevation of the ground"

bybarnyz

The watch exists to measure the length of time, and it is not thought that there are other uses for it. But,strontiumUltrahigh accuracy using atoms"Light grating" atomic clockIt seems that you can measure the elevation of the height of a mountain if you use it.

Geodesy and metrology with a transportable optical clock | Nature Physics
https://www.nature.com/articles/s41567-017-0042-3

Scientists take an atomic clock on the road and use it to measure the height of a mountain
http://www.latimes.com/science/sciencenow/la-sci-sn-atomic-clock-gravity-20180212-story.html

University of HannoverChristian LisdattProfessor 's research group is improving the light grating atomic clock to be carried outside the laboratory and is challenging the project to measure altitude outdoors. According to Einstein's theory of relativity, the flow of time isDepending on the magnitude of gravityTo do. Time flows slowly in places where gravity is large and time flows slowly in places where gravity is small. For example, the time flowing on the surface of the earth and the artificial satellite orbiting on the orbit of the universe are slightly out of time . Even if you do not leave the outside of the atmosphere, even a slight difference in elevation will make a difference in gravity. People living on the top of the mountain and people living just behind the coast have a faster flowing time over the mountains with lower gravity, so strictly the people who live above the mountain will get aged faster.

Scripps Oceanographic Research InstituteGeophysicistsDuncan Agnew"The idea of ​​measuring altitude with an atomic clock has been considered for a long time, and this research has actually shifted the long-term idea to practice."

According to Mr. Agnew, if two watches are placed in a place with an altitude difference of 1,000 meters, there will be a gap of 31 millionths of a second between the two clocks in 10 years. Although it is a level error which can not be observed with ordinary watches, it is said that this error can be detected by using highly accurate light grating atomic clock. "I call the clock, but actually does not do the work to read the scale and the needle, it measures the frequency of the atom at two points with the difference in elevation," explains Mr. Agnu. .

byhalfrain

Atomic clock uses peculiar atom specific frequency instead of pendulum clock pendulum clock and measures time with high precision. The frequency emitted by an atom is a very basic nature and constant everywhere in the universe. In the photonic lattice atomic clock using the strontium atom, it is possible to measure the time in units of 9 billion 1 second by confining strontium atoms in the lattice surrounded by the laser beam and measuring its frequency. If you prepare two clocks with such precision, you can determine the difference in elevation in principle by measuring the time gap caused by the difference in gravity at two different altitudes.

However, the problem is that the high precision light lattice limit shape can usually be maintained only in the laboratory. A stable environment is indispensable to keep the strontium atom close to absolute zero in a vacuum room and to lock it in the lattice created by laser light. If you move it, you can not maintain the state of the light lattice atomic clock, and the clock gets crazy. Professor Lisdat decided "to make a portable light grating atomic clock" and started this project.

Ultimately, Professor Lisdatt succeeded in storing a portable light grating atomic clock in a trailer capable of carrying two horses. "It's like a portable laboratory," says Lisdatt.


The group of Professor Ridddat brought a portable atomic clock that it made portable into the laboratory built in the French Alps. From there, it was connected with another optical lattice atomic clock in Turin, Italy, about 55 miles (about 90 km) away, and we decided to measure the deviation of the atomic clock. Professor Lisdat said, "I thought the experiment will be successful because there is a considerable difference in elevation."

However, due to the influence of tunnel construction in the vicinity, unexpected vibration occurred and affected the observation. Also, keeping the watch at a constant temperature has become more challenging than anticipated, so experiments are difficult. Nevertheless, it seems that the light grating atomic clock that we have carried shows that it is installed at the altitude 1000 m higher than the light lattice atomic clock in Turin.

"There were things that did not go well, but I was able to learn a lot of things accordingly and I was able to take the first step of altitude measurement with the light grating atomic clock," he says. The research team will improve the accuracy of the portable light grating watch and we expect to be able to measure altitude differences of 1 cm in the future. If applied, it will be useful for building a higher performance navigation system.

Human beings have made miniaturized watches that they were unable to carry once, made them portable like pocket watches and wrist watches. The same thing is also realized in the field of atomic clocks.

byJon Newman