According to quantum mechanics, vacuum is not just empty space. In fact, it is filled with quantum energy, and particles, are tiny particles constantly appearing and are also disappearing and leaving behind a trail of signals, which we call quantum fluctuations. Decades, these fluctuations exist only in our quantum theories, while in 2015, the researchers have not announced that directly they were found and identified. And now the same team of scientists claims to have advanced in their studies much further and were able to conduct a manipulation by vacuum and to determine the changes in these mysterious signals from the void.
Here we enter the territory of the high-level physics, but more importantly, if the results of the experiment, which we will talk today, is confirmed, it is quite possible, it would mean that scientists have discovered a new method of observation, interaction and practical inspections of the quantum reality without the intervention of it. The latter is particularly important, as one of the biggest problems of quantum mechanics and our understanding of it – is that every time we try to measure or even to observe a quantum system, this impact we are going to destroy it. As you know, it’s not too fit with our desire to know what is actually happening in a quantum world.
And from that moment, in comes the quantum vacuum. But before moving on, let us briefly recall what the vacuum from the point of view of classical physics. Here it is a space completely devoid of any matter in which the energy of the lowest values. There are no particles, and therefore nothing can interfere with or distort the pure physics.
One of the conclusions of one of the most fundamental principles of quantum mechanics – Heisenberg’s uncertainty principle sets a limit of accuracy of observation of quantum particles. Also under this principle, the vacuum is not empty space. It is filled with energy and pairs of particles-antiparticles appearing and disappearing randomly. These particles are rather virtual than physically tangible, and that is why you can’t find them. But even despite the fact that they remain invisible, as most of the objects of the quantum world, they also have an impact on the real world.
These quantum fluctuations create a fluctuating random electric field can affect the electrons. And because of that their exposure to scientists an indirect way demonstrated their existence in the 1940-ies.
In subsequent decades it remained the only thing we knew about these fluctuations. However, in 2015, a group of physicists working under the direction of Alfred Leitenstorfer from Constance University in Germany, said that we were able to directly determine these fluctuations by monitoring their effects on a light wave. The results of the research were published in the journal Science.
In their work the researchers used a short-wave laser pulses with duration of few femtoseconds, which they sent into the vacuum. Researchers began to notice subtle changes in light polarization. According to researchers, these changes were directly caused by quantum fluctuations. The result of observations will surely be controversial, but the scientists decided to bring his experiment to a new level by “compression” of vacuum. But this time they began to see strange changes in the quantum fluctuations. It turns out that this experiment wasn’t simply another confirmation of the existence of these quantum fluctuations — there are already can be a question that scientists have discovered a way of monitoring the experiment in the quantum world, without affecting the final result, that in any other case would destroy the quantum state of the observed object.
“We can analyze the quantum States without changing them, at the first observation,” says Leitenstorfer.
Typically, when you want to trace the influence of quantum fluctuations on the particular particles of light, you first need to detect and isolate these particles. This, in turn, will remove “quantum signature” of these photons. A similar experiment was conducted by a team of scientists in 2015.
In the framework of the new experiment is the observation of changes in the quantum fluctuations by absorption or amplification of light photons, the researchers were monitoring the light from the point of view of time. May sound strange, but in the vacuum of space and time operate in such a way that the observation immediately allows one to learn more about the other. Taking this observation, the scientists found that the “compression” of vacuum, this “compression” was absolutely the same as it happens when you compress a balloon, accompanied by quantum fluctuations.
At some point, these fluctuations are much stronger than the background noise uncompressed vacuum, and in some places weaker. Leitenstorfer leads the analogy of traffic moving through the narrow road space with cars in their lanes occupy the same lane to squeeze through a narrow place, and then are leaving for their lanes. The same thing to a certain extent, according to the observations of scientists, is happening in a vacuum: the vacuum compression in one place leads to the distribution changes of the quantum fluctuations in other places. And these changes can either accelerate or slow down.
This effect can be measured in the space-time section, as shown in the chart below. The parabola in the center of the image indicate the point of “compression” in a vacuum:
The result of this compression, as can be seen in the same image are some “sagging” in the fluctuations. No less surprising to the scientists was the observation that the level of power fluctuations in some areas was below the level of background noise, which, in turn, lower than that of the ground state of empty space.
“Because the new measurement method does not imply the capture or amplification of photons, there is the possibility of direct determination and monitoring of the electromagnetic background noise in a vacuum, and controlled by deviations of the States created by the researchers,” the study says.
Currently, the researchers checked the accuracy of your measurement method, as well as trying to understand what he is really capable of. Despite the already more than impressive results of this work, there is still a possibility that scientists have come to call “weak measurement technique”, which may be able not to disturb the quantum States of objects, but at the same time not able to tell scientists more about a particular quantum system.
If the method will really work, the scientists want to use it to measure “the quantum state of light” — the invisible light behavior at the quantum level, which we are only beginning to understand. However, further works are required additional verification, replication of results of the opening team of researchers from the University of Constance, and thereby demonstrate the suitability of the proposed measurement method.