Physicists have looked into "full emptiness" and proved that there is something there
According to quantum mechanics, the vacuum - not just an empty space. In fact, it is filled with energy and quantum particles, tiny particles that are constantly appearing and disappearing as well, and leaves behind a legacy in the form of signals, which we call quantum fluctuations. For decades, these fluctuations have existed only in our quantum theories, while in 2015, researchers announced that they have discovered and directly identified. Now, the same team of scientists says it has advanced in their studies much further - could hold manipulation by the vacuum and to identify 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, confirmed, quite possibly, it will mean that scientists have discovered a new method of observation, interaction and practical tests of quantum reality without interfering with 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 the quantum system, this impact, we will destroy it. As you can imagine, it's not too fit with our desire to know what is really going on in the quantum world.
And from that moment to the rescue comes the quantum vacuum. But before going any further, let us briefly recall that such a vacuum in terms of classical physics. Here it is a space that is completely devoid of any substance and having the lowest energy value. There are no particles, and therefore nothing can hinder or distort the pure physics. One of the conclusions of one of the most fundamental principles of quantum mechanics - the Heisenberg uncertainty principle - sets a limit on the accuracy of the observation of quantum particles. Also according to this principle, the vacuum is not empty space. It is filled with energy, as well as pairs of particles-antiparticles appearing and disappearing at random. These particles are more of a "virtual" rather than physical material, and that is why you can not find them. But despite the fact that they remain invisible, like most of the objects of the quantum world, they also have an impact on the real world.
These quantum fluctuations create randomly fluctuating electric field capable of acting on the electrons. And due to this they are exposed for the first time scientists have indirectly demonstrated their existence in the 1940s.
In the following decades it was the only thing we knew about these fluctuations. However, in 2015 a group of physicists who worked under the direction of Alfred Lyaytenstorfera of the University of Konstanz in Germany, said it could directly determine these fluctuations by observing their effect on light waves. The results of the work of scientists published in the journal Science.
In their work the researchers used a short-duration laser pulses only a few femtoseconds, which they sent to the vacuum. The researchers began to notice subtle changes in the polarization of light. According to researchers, these changes were directly caused by quantum fluctuations. Result observation probably more than once will cause controversy, however, scientists have decided to bring the experiment to a new level by "compression" of the vacuum. But this time they began to observe strange changes in the quantum fluctuations. It turns out that this experiment is not simply appeared one more confirmation of the existence of these quantum fluctuations - like here may already be a question that scientists have discovered a way to monitor the progress of the experiment in the quantum world, without affecting the end result is that in any other case destroyed the quantum the state of the observed object.
"We can analyze quantum states without modification at the first observation," - commented Lyaytenstorfer.
Usually, when you want to trace the influence of quantum fluctuations on specific commitments particles of light, you first need to detect and identify these particles. This, in turn, removes the "quantum signature" of these photons. A similar experiment was conducted by a team of scientists in 2015.
As part of the new experiment, instead of observing the changes in the quantum fluctuations by absorbing photons or amplification of light, researchers monitored the light itself in terms of time. It may sound strange, but in a vacuum space and time act in such a way that the observation of one right lets you learn more about the other. By keeping this observation, they found that in a "compression" of the vacuum is "compression" occurred absolutely the same manner as it occurs in compression balloon only accompanied by quantum fluctuations.
At some point, these fluctuations become stronger than the background noise uncompressed vacuum, and in some places, on the contrary, is weaker. Lyaytenstorfer cites as an analogy traffic jam, moving through the narrow space of the road: with time cars standing in their bands occupy the same band to squeeze through the bottleneck, and then parted on the bands. The same, to some extent, according to observations scientists happens in vacuo: the vacuum compression in one location leads to a distribution of the quantum fluctuations of changes in other locations. And these changes can either accelerate or slow down. This effect can be measured in a space-time cross-sectional view as shown in the chart below. Parabola in the center of the image shows the point of "compression" in a vacuum:
The result of this compression, as can be seen in the same image, are some of the "sagging" in the fluctuations. No less surprising for the scientists turned and seeing what power level fluctuations in some places was below the level of background noise, which in turn is lower than that of the ground state of empty space.
"Since the new method of measurement is not intended to capture or amplification of photons, there is the possibility of directly determining and monitoring the electromagnetic background noise in a vacuum, as well as deviations of controlled states created by researchers", - stated in the study.
At the moment, the researchers checked the accuracy of their measurement method, as well as trying to make sense of what he is really capable of doing. Despite the already more than impressive results of this work, there is still a possibility that the scientists have called "unconvincing measuring method", which is, perhaps, able to not disrupt the quantum state of the objects, but at the same time not able to tell scientists more about a particular quantum system.
If the method really will work, the scientists want to use it to measure the "quantum state of light" - the invisible behavior of light at the quantum level, which we are only just beginning to understand. However, further work is needed additional check - Replication of the results of opening team of researchers from the University of Constance and thereby demonstrate the suitability of the proposed measurement method.