If we put it into operation in ‘zero year’, it would be ticking steadily and not deviate for a thousand times the age of the universe.
Tempus fugit. From the dawn of humanity, we have regulated our rhythms and behaviors to the compass of the Earth itself, and in turn, the human species has tried to create tools and, later, technology capable of measuring as accurately as possible the cyclical activity of space-time that surrounds us.
To this day, the human has achieved the most accurate clock he has ever created. But it’s not as you might imagine: it’s a quantum gas cube.
To understand this, let’s analyze what has been the most accurate clock so far. It was created in 2015, and had extreme precision: less than a second in fifteen billion years (much more than the age of the universe, thirteen thousand eight hundred million years). It was also designed from strontium atoms.
Earlier atomic clocks were created with cesium atoms, which were considered quite accurate: in them, the calculation of time is based on the duration of the energy changes of electrons in atoms. Each change is a cycle, and a second is officially considered about nine billion cycles of a cesium atom.
Now, the new atomic clock of strontium atoms, designed by a team from the University of Colorado and led by scientist Jun Ye, has a far greater precision than the 2015 clock: If we put it into operation in year zero, it would be ticking steadily and without deviating for a thousand times the age of the universe.
It works as follows: the scientists placed the strontium atoms in a grid pattern and then stacked them into towers, in a three-dimensional structure, much more efficiently than previously the cesium atoms were placed: namely, ten million of atoms per cubic centimeter.
How does time measure these types of watches?
Tic-tac is measured by microwaves emitted by electrons around atoms, which jump from a lower orbit to a higher one, as they absorb and then lose energy from a laser.
And what was wrong with the clocks of cesium atoms?
The truth is that the precision with which cesium electrons can measure time has a speed limit: they can jump back and forth ‘only’ nine billion times a second. Electrons in strontium atoms, on the other hand, can travel almost one million times per second.
Therefore, in the new clock, the 3D structure in which the strontium atoms grouped allowed them to measure signals of more atoms simultaneously within the width of the laser beam: ten trillion atoms per cubic centimeter compared to previous clocks, with ten billion atoms per cubic centimeter.
In addition, the researchers cooled the atoms to -273 degrees Celsius (the physically attainable limit or ‘absolute zero’) and trapped them at a fixed location to control the interactions between them. “Imagine a scenario where you have a home for a single person in a block of the city. One person lives in each house and the neighbors are never allowed to enter,” explain you. “Each atom fits into a particular site.”
Ultra-low temperatures convert atoms into what is known as a quantum gas. “When the atoms are in the gaseous phase they are very hot, they are separating and colliding with each other,” he says. “This changes when the temperature of the gas is lowered, so much that these particles begin to move like waves, avoiding each other”.
And, all this, results in the most accurate clock in the world : only three and a half times out of ten quintillones would be delayed; or, what is the same, only four tics in ten raised to nineteen.
What is the use of such an extremely accurate watch?
Having clocks that are not delayed even a second in time, since the universe was formed, is vital to prove theories like Einstein’s General Relativity. In addition, clocks of such enormous precision, which remain accurate for billions of years, can have many different applications: meteorology, radio astronomy, and the basis of GPS.