From today it is possible to know the time with a precision never reached before. At the National Institute of Standards Adn Technologists (Nist) American, in fact, have just presented a record atomic clock, capable of keeping time with an accuracy that reaches the 19th decimal. To do this, use a laser beam over three kilometers long, and an aluminum ion trapped in an electromagnetic field in the company of a magnesium atom. Thanks to its very precise measurements, in the future it could revolutionize fields ranging from cosmology, to the development of quantum computers.
So the aluminum atom marks the time
Unlike a traditional atomic watch, which uses microwave to measure the resonance frequency of Cesio-133, the new record watch is a so-called “optical watch”, that is, it uses visible light and an atom with much higher resonance frequency, in this case aluminum. The greater the frequency, the greater the precision. And this makes atoms like aluminum ideal as a timepiece.
But to use them there are at least two problems to overcome: they must be cooled practically at absolute zero and maintained in the void, to prevent the temperature or other atoms present in the air from interfering with measurements. To do this, electromagnetic fields are used that work as a traps, in which a single atom of the chosen and cooled element is imprisoned using laser.
What is the Ionian trap of the new clock
In the case of aluminum, these operations are relatively complex, because it is an element that the nist researchers define as “shy”, difficult to measure and cool with the laser. For this reason, as described in an article published in Physical Review Letters, they have decided to pair it with another element more sensitive to the action of laser, magnesium, in a scheme called “quantum logic spectroscopy”, which allows you to transfer quantum information between two atoms within an Ionian trap (the electromagnetic field we were talking about a little while ago) and therefore to use the easier one to manipulate, modify and measure the other.
Once in this way an atomic clock with innovative design was obtained, it was therefore necessary to optimize each part of its parts to achieve the record results sought by its inventors. The Ionian trap in which the two atoms are contained has been perfected to eliminate any micro -signization that could interfere with the accuracy of the clock. And the perfected laser to make it more stable. Using more than three kilometers of optical fiber to improve their performance to the point of shortening from three weeks to a day and a half the time necessary to obtain precise measurements to the nineteenth decimal.
It will help us to know the planet Earth better
The new watch, according to its inventors, is 41 percent more accurate than its predecessors and 2.6 times more stable. And with similar numbers, it is ready to revolutionize a multitude of research sectors. The quantum technologies on which it is based will be a test bench to study new concepts in quantum physics, and develop quantum computers of the future. Not only that, because so much precision in measuring the flow of time also makes it extremely sensitive to the variations of the gravitational potential (the more you approach a powerful gravitational field, the more time slows down, as Einstein taught us). And it can therefore be used to map the shape of the Earth with extreme precision (a field known as Geodesia), or to measure the position of our planet in space with a waste of just one centimeter. Or again, to test the most essential theories of physics and cosmology.
“It is exciting to work on the most accurate watch ever,” comments Mason Marshall, a nist researcher who collaborated in the construction of the new atomic clock. “These long -term projects on precision measurements – he explains – can really push the field of physics forward and our understanding of the world around us”.
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