domingo, 7 de octubre de 2012

The Mysterious 'Majorana Fermion' --At the Border Between Matter & Antimatter


In 1938 one of the world's greatest scientists withdrew all his money and disappeared during a boat trip from Palermo to Naples. Whether he killed himself, was murdered or lived on under a different identity is still not known. But no trace of The Italian physicist Ettore Majorana has ever been found.

Majorana was a brilliant theorist who in the 1930's showed great insight into physics at a young age. He discovered a hitherto unknown solution to the equations from which quantum scientists deduce elementary particles: the Majorana fermion. Majorana deduced from quantum theory the possibility that there must be a special particle that would be right on the border between matter and antimatter.

Fast forward to February 2012, the mysterious Majorana fermion was detected in a nanowire, according to Dutch nanoscientist Leo Kouwenhoven. The discovery could confirm the theory that assumes that dark matter, which is thought to form about 73 percent of the Universe, is composed of Majorana fermions. 
Kouwenhoven leaked  preliminary results of his research at a scientific congress. On April 12, Kouwenhoven went public in Science Express, saying his team at at TU Delft’s Kavli Institute and the Foundation for Fundamental Research on Matter (FOM Foundation) — and also financed by Microsoft — had created a nanoscale electronic device in which a pair of Majorana fermions magically (my word) “appear” at either end of a nanowire.
The recipe was simple: take one nanowire (made by colleagues from Eindhoven University of Technology) and add a superconducting material and a strong magnetic field.
Quantum computer experts say that Majorana fermions could be fundamental building blocks for a future quantum computer that would be exceptionally stable and barely sensitive to external influenceswould avoid the decoherence. challenge facing all current quantum computers.
Kouwenhoven’s team hopes to use a scheme called “topological quantum computation” that could evade decoherence at the hardware level by storing quantum information non-locally, which could lead to a Nobel Prize for Kouwenhoven and total domination of the future of quantum computing by Microsoft. 
Practically all theoretic particles that are predicted by quantum theory have been found in the last decades, with just a few exceptions, including the enigmatic Majorana particle and the well-knownHiggs boson being sought by CERN"s massive LHC project.

On June 7, 2011 Italian media reported that the Carabinieri‘s RIS had analyzed a photograph of a man taken in Argentina in 1955, finding ten points of similarity with Majorana’s face. The mystery of the Majorana fermion lives on! 
The image below shows two Majorana fermions (orange balls) are formed at the end of the nanowire. Electrons enter the nanowire from the Gold contact, and meet the Majorana fermion on the way. If the electron has the wrong energy, it is reflected back into the contact. If it has the right energy, it can go through the Majorana fermion via a special interaction. 

Source: The Daily Galaxy via, and Ref.: V. Mourik, et al., Signatures of Majorana Fermions in Hybrid Superconductor-Semiconductor Nanowire Devices, Science, 2012; [DOI:10.1126/science.1222360]
Image credit: TU Delft

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