What Is an Atomic Watch?

Atomic clock is a timing device with an accuracy of 1 second every 20 million years. It was originally created by physicists to explore the nature of the universe; they never thought that this technology could one day Global Navigation System.

What people usually use

Until the 1920s, the most accurate clock relied on

A study published by the US "Science" magazine on July 12, 2001 showed that US government scientists have combined advanced laser technology with a single mercury atom to develop the world's most accurate clock. Scientists at the National Institute of Standards and Technology in Boulder City, Colorado, USA have developed this new type of atomic clock based on high-frequency invisible light waves and non-microwave radiation. Since the development of this clock mainly relies on laser technology, it was named "All Optical Atomic Clock".

We know that the "tick" of atomic clocks comes from atomic transformations. In current atomic clocks, cesium atoms are transformed in the microwave frequency range, and optical transformations occur in a much higher frequency range than microwave transformations, so it can provide A finer time scale allows for more precise timing. This newly developed all-optical atomic clock hand makes a "tick" sound when it moves within 1 second to the fifth power of one thousand (the number obtained by adding 15 zeros after 1) is the highest level now Clock-one hundred thousand times the microwave cesium atomic clock. Therefore, it will be much more accurate to use it to measure time.

The construction of all clocks includes two major parts: devices that can move according to a fixed period, such as a pendulum; and some devices that calculate, accumulate, and display the loss of time, such as the gears that drive the clock hands. The atomic clock, which was first developed about 50 years ago, adds a third part, the atoms that respond to light and electromagnetic radiation at specific frequencies. These atoms are used to control the "pendulum." At present, the most advanced atomic clock is to use 1 million liquid metal cesium atoms to respond to microwave radiation to control the movement of the clock hands. Such a clock hand moves about 10 billion times per second. The faster the clock hand moves, the more accurate the time calculated by the clock. But the high-speed electronics technology used in cesium atomic clocks cannot count more clock hands. Therefore, in the study of the new all-optical atomic clock, American scientists did not use cesium atoms, but a single cooled liquid mercury ion (that is, a mercury atom that lost an electron), and compared it with the femtosecond of a pendulum (one thousand One trillionth of a second) The laser oscillator is connected, and the clock is equipped with an optical fiber, which can break the optical frequency into microwave frequency pulses that can be recorded by the counter.

To make such an atomic clock, a technology that can capture the corresponding ions and keep the captured ions sufficiently stationary to ensure accurate reading of the data, and at the same time to ensure that the number of "ticks" can be accurately calculated at such a high frequency. The quality of this clock depends on its stability and accuracy, that is, the clock must provide a constant output frequency and make its measurement frequency consistent with the resonance frequency of the atom.

"We have demonstrated for the first time the principle of this new generation of atomic clocks, which may be 100 to 1000 more accurate than current microwave cesium atomic clocks," said American physicist Scott Diddams, who led the study. Times. "It can calculate the shortest time interval ever. Scientists predict that this clock can improve the application level of aeronautical technology, communication technology, such as mobile phones and fiber-optic communication technology. At the same time, it can be used to adjust the precise orbit of satellites, aviation in outer space, and connecting space ships.

Developed by the Joint Laboratory of the Astrophysics Institute of the University of Colorado, Strontium Lattice Atom

5 billion years of strontium lattice atomic clock

Zhong, the previous record holds the quantum logic clock developed for the National Institute of Standards and Technology, but the strontium lattice atomic clock is more accurate than the latter, and the accuracy can be increased by 50%.

Dr. Jun Ye of the Institute of Astrophysics believes that the strontium lattice atomic clock is controlled by the atomic oscillation between two energy levels, and the conversion between the energy levels is precisely controlled by a laser device, which achieves the most accurate clock manufacture. In fact, the goal of scientists is to create a clock that will never go wrong. The goal is not 5 billion years, but the age of the entire universe. fast.