Scientists have denied the discovery of "angel particle"

Scientists have denied the discovery of "angel particle"
Scientists have denied the discovery of "angel particle"
Anonim

The existence of the Majorana fermion - a special particle that is at the same time its own antiparticle - was first suggested by the Italian scientist, physicist Ettore Majorana in 1937. In honor of him, this mysterious fermion got its name.

At the time of Majorana, this particle was a mental construct: it was then impossible to verify its existence. Today scientists are trying to find confirmation of the hypothesis. Particle physicists want to find out if a subatomic neutrino could be an "angel particle", and condensed matter physicists hope to find signs of the existence of particles with Majorana properties using solid-state devices that combine exotic quantum materials with superconductors.

Fermions are important to condensed matter physics because their incredible properties could help build a topological quantum computer. The qubits of such a computer would by their nature be protected from one of the main problems in creating quantum computers - decoherence of the environment (loss of information that occurs if the quantum system is not completely isolated).

In 2017, it was announced that it was possible to conduct experiments that showed traces of the activity of "angel particles". Physicists at the University of Pennsylvania, in collaboration with colleagues at the University of Würzburg, Germany, checked the data on which the claim was based and found that the interpretation of the experimental results could be erroneous. The team analyzed the operation of devices based on a "quantum anomalous Hall insulator" - a material in which electric current flows only along the edge. It was on the results of experiments with such devices that the proofs of the registration of the existence of the Majorana fermion were built.

The 2017 work criticized by the authors of this article believed that if the boundary current is in pure contact with the superconductor, propagating chiral Majorana particles arise, and the electrical conductivity of the device should be "semi-quantized" (the value e2 / 2h, where "e" is the electron charge, and " h "is Planck's constant) when subjected to an accurate magnetic field.

An analysis of scientists from Pennsylvania and Würzburg, who studied more than 30 devices with several configurations of materials, showed that devices with a pure superconducting contact will always show a semi-quantized value, regardless of the conditions of the magnetic field. The superconductor simply acts like an electrical short circuit, and what is happening does not indicate the presence of a Majorana fermion.

Scientists note that their work does not negate the theoretical possibility of the particle's existence. They even suggest that the combination of quantum anomalous Hall insulators and superconductivity may still contribute to the registration of traces of this existence - but not in its current form. The design of the 2017 experiment is reasonably questioned, given that two laboratories at once received consistent results that refute its conclusions.

The authors say their work is an important and compelling example of how rigorously validated data is, especially where it is tempting to claim a high-profile discovery. “This is a great illustration of how science should work. Sensational claims about the discovery need to be carefully checked and reproduced,”concludes Penn State University professor Nitin Samart.

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