In 1937, just one year before suddenly disappearing under mysterious circumstances, a brilliant italian physicist named Ettore Majorana predicted the existence of a very peculiar particle. Having the exciting property of being its own antiparticle (that is it simultaneosly behaves as matter and anti-matter) the elusive “Majorana particle” has been finally observed by a group of scientists at Princeton University (Nadj-Perge 2014). To achieve the important result they used a two-story-tall microscope to observe the end of a superconducting wire.
The appearance of the peculiar particle in superconducting wires was predicted in 2001 by KITP/Caltech physicist Alexey Kitaev (Kitaev 2001). First indications of the existence of the particle came from experiments conducted in 2012 at Delft University by the team of Leo Kouwenhoven (Mourik 2012), but only this latest work could put the discussion on the existence of the particle to rest. However this is just the start. The importance of the discovery is related to the special nature of the Majorana particle, which cannot possess intrinsic electric charge and has only a minimal interaction with electromagnetic fields. Therefore this makes the particle a potential candidate for dark matter, which is believed to make up for almost 85 percent of the mass content of the Universe, but so far eluded detection. Majorona particles, again due to their minimal interaction with the rest of the world, could also help scientists to build quantum computers. While nobody is really sure what happened to Ettore Majorana ("Ettore was too intelligent. If he has decided to disappear, no one will be able to find him" - E.Fermi (Holstein 2009)), it is clear his legacy will keep driving important scientific progress for years to come.
A Yu Kitaev. Unpaired Majorana fermions in quantum wires. Phys.-Usp. 44, 131–136 Uspekhi Fizicheskikh Nauk (UFN) Journal, 2001. Link
Barry R Holstein. The mysterious disappearance of Ettore Majorana. J. Phys.: Conf. Ser. 173, 012019 IOP Publishing, 2009. Link
V. Mourik, K. Zuo, S. M. Frolov, S. R. Plissard, E. P. A. M. Bakkers, L. P. Kouwenhoven. Signatures of Majorana Fermions in Hybrid Superconductor-Semiconductor Nanowire Devices. Science 336, 1003–1007 American Association for the Advancement of Science (AAAS), 2012. Link
S. Nadj-Perge, I. K. Drozdov, J. Li, H. Chen, S. Jeon, J. Seo, A. H. MacDonald, B. A. Bernevig, A. Yazdani. Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor. Science American Association for the Advancement of Science (AAAS), 2014. Link