A new study explains that in the quantum world due to entropy, a system could head both forward and backward.
Quantum is the future and the importance of learning about quantum computing today is undeniable.
But it’s time to explore other important aspects of this vast topic.
Humans are accustomed to viewing the concept of the flow of time as something that only flows toward the future. In the quantum world, however, things could be different.
But now, a new study published in Communications Physics, in fact, a team of researchers from the Universities of Bristol, Vienna, Balearic Islands and the Institute for Quantum Optics and Quantum Information (IQOQI-Vienna) explained that quantum systems can evolve simultaneously along with two opposite time arrows, that is, both forward and backward in time.
In the classical world, the experience seemed to leave no doubt that time existed and moved forward. Indeed, in nature, processes tend to evolve spontaneously from states with less disorder to states with more disorder, and this, in physics, is described in terms of “entropy,” which is the physical characteristic that defines the amount of disorder in a system.
This slope can be used to identify a time direction, meaning that this flows from the past into the future in parallel with the increase in disorder. However, in the quantum realm, things are no longer so well defined.
“If a phenomenon produces a large amount of entropy, observing its temporal reversal is so unlikely as to become essentially impossible. However, when the entropy produced is small enough, there is a non-negligible probability of seeing the time-reversal of a phenomenon occur naturally,”
explains Giulia Rubino, a researcher at the Quantum Engineering Technology Labs (QET Labs) at the University of Bristol and the lead author of the study
“We can take as an example the sequence of things we do in our morning routine. If we were shown our toothpaste moving from the toothbrush into its tube, we would have no doubt that this is a rewound recording of our days. However, if we gently squeezed the tube so that only a small portion of the toothpaste leaked out, then it would not be so impossible to watch it re-enter the tube, sucked in by the decompression of the tube. This example allows us to understand how the greater the disorder in the system, the less likely we are to see its temporal inverse in nature.”
The researchers applied this idea to the quantum realm, one of whose peculiarities is the principle of quantum superposition, according to which if two states of a quantum system are both possible then that system can also be in both states at the same time.
Thus, they discovered that in the quantum realm, time can evolve towards both the future and the past and can do so simultaneously. In other words, a quantum system can evolve simultaneously along with both directions of time.
Scientists have therefore realized that, at the most fundamental levels of matter, it is no longer possible to distinguish so well between the future and past time directions.
The results of this study, which show that the arrow of time at the quantum level depends on the production of entropy, could also prove useful at the practical level, particularly in quantum thermodynamics and in the construction of new coolant-type thermal devices.
The quantum realm could be as wide as interesting and its importance in technology is undeniable; it could actually solve problems that seem impossible today.
Learn more about the basics of quantum computing with Francesco Sisini.
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