A team of physicists quantum superpositions produced experimentally by simply using a mirror.
standing before a mirror, we can easily distinguish our mirror image. The mirror does not affect our movement in any way. For quantum particles, this is much more complicated. In a spectacular experiment in the laboratories of the University deHeidelgerg, a group of physicists at the University of Heidelberg, together with colleagues University of Munich and Vienna University extended a thought experiment of Einstein and managed to blur the distinction between a particle and its mirror image. The results of this experiment have been published in the journal Nature Physics .
light emitted atom in Reverse.
When an atom emits light in the form of a photon in a particular direction, suffering a setback in the opposite direction. If you measure the photon, the atom movement is also known [to the limits of the Heisenberg uncertainty but] Scientists placed atoms near a mirror. In this case, there are two possible paths for any photon traveling toward the observer: it could have been delivered directly in the direction of the observer, or may have traveled in the opposite direction and then been reflected in the mirror. If there is no way to distinguish between these two scenarios, then the atom motion is not determined, the atom is moving in a superposition of both paths.
"If the distance between the atom and the mirror is very small, it is physically impossible to distinguish between these two paths," explains Jiri Tomkovic, PhD student at the University of Heidelberg. The particle and its mirror image and can not be clearly separated. The atom moves toward the mirror and away from it at the same time. This may sound paradoxical, and certainly it is impossible in classical mechanics for macroscopic objects, but in quantum physics, such overlays are a well known phenomenon. "Uncertainty about the state of the atom does not mean that as lack of accuracy," emphasizes Jörg Schmiedmayer, University of Vienna. "It is a fundamental property of quantum physics: the particle is in both possible states simultaneously, is superimposed." In the experiment, the two possible states of motion atom, one to the mirror and the other away from it, are combined using Bragg diffraction produced by a diffraction grating made with a laser. Noting the interference, it can be shown directly that the atom really has traveled both paths simultaneously.
by a different route at a Time
This reminds us of the famous double-slit experiment, in which a particle reaches a sheet with two slits and passes through both simultaneously, because the properties of wave-particle duality. Einstein had already argued that this could only be possible if no how to determine which path the particle is actually chosen, even precise measurements of a small decrease of the sheet with two slits. As soon as there is a theoretically possible to determine the path of the particle, the quantum superposition is destroyed. "In our case, photons play a role similar to the double slit," said Markus Oberthal, University of Heidelberg. "If light can, in principle, give information about the motion of the atom, then the movement is determined without ambiguity. Only when it is essentially undecidable, the atom may be in a superposition state, combining both." And this undecidability is guaranteed by the glass, which absorbs the photon momentum.
Quantum Effect - Using just a mirror
Test under what conditions such quantum superpositions can be created has become a topic of great importance in quantum physics. Obertal Markus Jörg Schmiedmayer and devised the experiment had already made a few years. "The fascinating thing about the experiment, scientists say, is the possibility of creating quantum superposition states using only a mirror, without any external field." In a very simple and natural, the distinction between particle and its mirror image are blurred, without complicated operations performed by the experimenter.
Source: Physorg
0 comments:
Post a Comment