Experiment proves the wave-particle duality of antimatter

Double slit x ray simulation
Intensity distribution behind a double slit illuminated by a superposition of plane waves of 5 different photon energies. (Credits - Wikimedia Commons)

Antimatter is a material which is made of not only antiparticles but also waves. However, it has been recently found that this holds true even in the case of a singular particle of antimatter. The results of the experiments have been published in the Science Advances journal.

It has been long known by physicists that almost everything in existence, from light, other energy forms to individual particles of a human body exists both in the form of particles as well as waves. This is also known as the particle-wave duality. It has been verified for microscopic elements such as electrons, protons and even atoms and molecules. However, this is not detected in macroscopic elements due to their very short wavelengths. Quantum mechanics has its foundations in this duality of matter.

Physicists now have shown that a single positron which is the antimatter twin of an electron is composed of particles as well as waves. For proving this, scientists performed a modified version of the “double-slit experiment” which was done in 1927 by Davisson and Germer to prove that electrons have both particle as well as wave nature.

In the double-slit experiment, scientists focused a stream of electrons through a plate having two slits on it, and a detector behind the plate. If electrons were only composed of particles then, then there would have been two bright lines on the detector. But this was not the case. There was a spread-out formation on the screen with alternate bright and dim lines. Hence diffraction was observed. Waves can combine or cancel each other depending on how they overlap or shift in respect to the other one, which in turn creates a pattern which is known as interference. These experiments are called interferometry.

In 1976, scientists found out how to achieve the same results with only a single electron, which brings the conclusion that even individual electrons are actually waves which can interfere with themselves.

A team of Swiss and Italian researchers have found out how to create a low energy positron beam which could be used for conducting the first antimatter form of the famous double slit experiment. When the positrons were fired through a series of multiple slits, the pattern formed by the positrons was similar to the one which would have created by waves and not particles.

This leads to a new version of the interferometry experiments. Paola Scampoli, a researcher at Politecnico of Milano said the experiment proves the quantum-mechanical origin and hence the wave nature of the positrons.



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