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Physicists manage to measure time in a quantum instant

Time is one of the deepest mysteries that exists in the Universe. Although the fundamental laws of Physics do not distinguish between past and future, as Sean Carrol, a physicist at the California Institute of Technology (Caltech) argues, time is like an arrow that always points to the future , for some hidden reason. According to Ludwig Boltzmann, the cause could be related to the spontaneous increase in disorder in the Universe, entropy. But despite Boltzmann's attempt, we still do not know why the Big Bang started with such an orderly and compact state of energy (the least possible disorder), and why since then everything goes forward in time and never backwards.

Top Image: When a photon hits a helium atom, a quantum leap occurs and an electron is released, leaving the helium ionized. This occurs in a few attoseconds - TU WIEN

Updated version of the previous article.

If the cause of time going forward is elusive, so is the duration of an instant.

How precisely can you measure it ? Is there a perfect and objective measure? The theoretical limit is in the Planck time (the time a photon travels the Planck distance , which is in turn the minimum length in which the quantum effects of gravity begin to operate), but in reality it is not known : the answer to this enigma seems to lie between Physics and Philosophy. Luckily, this Monday Quantum Mechanics has made it possible to accurately measure one of the shortest moments so far. Specifically, scientists from the Technical University of Vienna, h n timed a quantum leap, a phenomenon that was thought to happen instantaneously a few years ago, but whose duration has now been established around five attoseconds, (one attosecond is 10 ^ -18 seconds, while one thousandth of a second is 10 ^ -3 seconds) . Their conclusions have been published in "Nature Physics".

"The most important advance of this study is the precision that has been achieved and that has proven to be an excellent confirmation between experiments and theory," explained Renate Pazourek , co-author of the study and researcher at the Vienna University of Technology to ABC . The experiments were carried out at the "Max Planck Institute of Quantum Optics" (in Munich, Germany), and researchers from the Department of Theoretical Physics of Condensed Matter, at the Autonomous University of Madrid (UAM), also participated .

As you have said, although it is known that there are even more ephemeral physical processes in the field of high-energy physics, until now it has never been possible to measure something so extremely brief with experiments.

Jumps within atoms

These jumps that they have measured are very fast changes of state that occur in quantum particles (like photons, the particles of light). They occur for example when an atom absorbs a photon, and as a result of that a change takes place: its electrons jump towards a state of superior energy (it is similar to what happens when light heats an object).

On this occasion, the scientists analyzed this phenomenon in helium atoms, quite simple atoms because they only have two electrons. More specifically, they saw what happened when these atoms were hit by a laser pulse . When that happens, the helium loses one of its electrons (it is said that it ionizes), and then the atom begins to behave in a different way (among other things, it acquires a great eagerness to capture other electrons).

In this case, and thanks to ultrashort laser pulses, the scientists were able to measure almost instantaneous temporal structures, and thus find out that this electron jump occurs in a matter of attoseconds.

"The precision of the experiment is better than one attosecond," Pazourek said. "This is the most accurate measurement yet of a quantum leap."

To make this measurement, the scientists took advantage of a property of the two electrons in helium. Both are correlated and connected by laws of Quantum Physics , so they are not independent particles. So when the laser hits the atom and one electron is "kicked out," the other electron gains some energy from the laser. "This remains in the atom, but in a higher state of energy," Stefan Nagele said in a statement.

Thanks to this, something else has also been discovered. The time required for quantum leaps is not always the same. When electrons gain energy, the process is faster (takes five attoseconds) than when they lose it.

In conclusion, the scientists believe that this experiment provides new clues in the physics of ultrashort timescales . Effects that until a few decades ago were thought to occur in an instant, but can now be measured, calculated and controlled. This will perhaps help to better understand the basic laws of nature, and perhaps open up new possibilities for manipulating matter on its quantum scale. It seems to be a matter of time.

Reference: QuantaMag, Nature Physics.

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