Physicists from Italy and Switzerland performed an experiment with a positron, similar to the experiment with two slits and an electron. The researchers demonstrated the paradox that a single particle interferes with itself, and proved that the quantum mechanical properties of antimatter are similar to those of ordinary matter. The results of the experiment are published in the arXiv.org repository.
According to wave-particle duality, electrons under different conditions can manifest the properties of waves and particles. Particles can be represented in the form of de Broglie waves, which characterize the probability of finding an object at a given point in space. Like any wave, de Broglie waves, when passing through narrow slits, can undergo diffraction and interference, in which two coherent waves are superimposed, resulting in an increase or decrease in their amplitudes. Thus, finding electrons at certain points becomes more or less likely.
The interference pattern, as in the classical Jung's experiment, arises even if particles are passed through a device with two slits one after another. Thus, the de Broglie wave determines the probability of a single particle hitting any part of the detector screen. In this case, it is often said that the particle interferes with itself. Although in theory antiparticles should exhibit the same properties, so far no one has demonstrated their interference in practice.
The experiment was carried out at the Italian Laboratory for Nanostructured Epitaxy and Silicon Spintronics (L-NESS). The radioactive isotope sodium-22 was used as a source of positrons (antiparticles of electrons). The particles were accelerated to energies of 8, 9, 11 and 14 keV and hit the Talbot-Lau interferometer. The device consisted of two collimators (long holes) designed to produce a narrow beam of particles; two diffraction gratings with different periods, an emulsion detector and a gamma-ray detector that captures radiation from positron annihilation when colliding with an emulsion.
Analysis of interference fringes obtained when particles hit the emulsion detector for 120-200 hours demonstrated the same picture of wave-particle duality that was observed in the classical experiment with two slits. According to the scientists, the results show that in the future it will be possible to create supersensitive devices based on the principle of operation of the Talbot-Lau interferometer to measure the previously unobserved gravitational interaction of antimatter with ordinary matter.