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Sina Tech News, February 10, Beijing time - According to a report by The Times of London, scientists have successfully developed a new generation of laser clocks that are extremely accurate in timing, with almost no error of even one second over a period of 2 billion years. This laser clock, which is the most precise to date, could be applied to satellite navigation in the future, maintaining an accuracy of within one meter when tracking moving targets on the ground.
This new type of clock designed and manufactured by scientists uses laser as the measurement reference, enabling a time error of no more than 1 second over a period of 2 billion years. In the future, this new type of clock can be widely applied to ground satellite navigation, making autonomous driving of cars possible. After the technology is mature, it can even achieve precise landing of unmanned aircraft. After achieving the above achievements, scientists from multiple countries such as the United States, Britain, Germany, France, and Japan are preparing to continue the competition in this research field in order to design and manufacture more precise clocks. Their goal is to make the clock time accurate to the minute and second since the Big Bang 13.7 billion years ago. Scientists believe that this kind of clock will be achieved within ten years. Since this new type of clock uses laser to measure and synchronize atomic vibration frequency, they are also commonly referred to as optical clocks. Through this technology, the clock can divide time into smaller components.
Previously, the world's most advanced clock was developed by the National Institute of Standards and Technology (NIST) in the United States. By measuring the vibrations of electrons in mercury ions, it can maintain precise operation for 1.7 billion years without any deviation in time. The most accurate timing device before was the atomic clock, which could achieve an accuracy error within one second for 80 million years. In contrast, an ordinary watch would have an error of about 15 seconds within a month. The International Bureau of Weights and Measures (BIPM) located in Paris, France, plans to replace atomic clocks with optical clocks by 2020. Elise Arias, the executive secretary of the BIPM responsible for time and frequency, said, "Optical clocks represent the future of clocks, which is a very exciting invention. By 2015, we will have taken
achieve phased results." The most important application of optical clocks may be in global satellite positioning systems, which are used to track aircraft, ships, cars, and other objects. Global satellite positioning systems receive microwave signals emitted by satellites and synchronize primarily by measuring the time it takes for the signals to arrive, enabling the locking of an object on the ground within a range of 10 meters.
Scientists believe that if optical clocks are installed on satellites, they can pinpoint targets to within 1 meter. This level of precision can be used for autonomous driving of cars or aircraft. Of course, beyond these applications, scientists have higher expectations for the use of optical clocks. They hope that optical clocks can help them test the fundamental laws of physics. According to Till Rosenband, a physicist at the National Institute of Standards and Technology in the United States, "Optical clocks can also be used to detect the fundamental properties of the universe. We can even rely on this level of precision to discover variations in the fundamental laws of physics." According to the fundamental principles of quantum physics, atoms absorb or emit electromagnetic energy based on the energy difference between different electron arrangements, that is, the energy difference between different electron shells around the nucleus. Here, electromagnetic energy is discrete. When an atom transitions from one "energy state" to a lower "energy state", it emits electromagnetic waves. The resonant frequency of the same type of atom is constant—for example, the resonant frequency of cesium-133 is 9192631770 cycles per second. Therefore, cesium atoms can be used as a kind of metronome to maintain highly precise time.
Ordinary clocks rely on a fixed vibration frequency to measure time. The balance wheel of a mechanical watch vibrates 5 or 6 times per second, while a tuning fork clock vibrates hundreds to thousands of times per second. The vibration frequency of a quartz clock is generated by the vibration of tiny quartz crystals, with a fixed vibration frequency of 32,000 times per second. The cesium atomic clock vibrates at a frequency of up to 9.19×10^9 times. The higher the vibration frequency, the more accurate the timing. In 1967, due to significant progress in atomic clock research, people began to redefine the second, based on the oscillation frequency of cesium atoms. Today's atomic clocks can achieve an accuracy of no more than 1 second per 100,000 years. In 2001, the National Institute of Standards and Technology (NIST) of the United States developed the first optical clock using laser instead of microwave. In 2004, scientists at the National Physical Laboratory of the United Kingdom made further improvements to this optical clock. In 2008, NIST developed a new type of optical clock that was 21 times more accurate than the most advanced atomic clock at that time. (End)