Tag Archives: V. Mourik

Majorana, matter, anti-matter, and nanowires

This is one of my favourite types of science story and I’m going to start with the quantum physics part of this (from the April 13, 2012 news item on Nanowerk),

Scientists at TU Delft’s Kavli Institute and the Foundation for Fundamental Research on Matter (FOM Foundation) have succeeded for the first time in detecting a Majorana particle. In the 1930s, the brilliant Italian physicist Ettore Majorana deduced from quantum theory the possibility of the existence of a very special particle, a particle that is its own anti-particle: the Majorana fermion. That ‘Majorana’ would be right on the border between matter and anti-matter.

The researchers have made a video about the Majorana fermion and nanowires (from the April 12, news release on the TU Delft website),

Here’s a little more about the Majorana fermion and why the researchers as so excited (from the TU Delft news release),

Majorana fermions are very interesting – not only because their discovery opens up a new and uncharted chapter of fundamental physics; they may also play a role in cosmology. A proposed theory assumes that the mysterious ‘dark matter, which forms the greatest part of the universe, is composed of Majorana fermions. Furthermore, scientists view the particles as fundamental building blocks for the quantum computer. Such a computer is far more powerful than the best supercomputer, but only exists in theory so far. Contrary to an ‘ordinary’ quantum computer, a quantum computer based on Majorana fermions is exceptionally stable and barely sensitive to external influences.

This breakthrough was achieved not with the Large Hadron Collider at CERN (European Particle Physics Laboratory) but with nanowires (from the TU Delft news release),

For the first time, scientists in Leo Kouwenhoven’s research group managed to create a nanoscale electronic device in which a pair of Majorana fermions ‘appear’ at either end of a nanowire. They did this by combining an extremely small nanowire, made by colleagues from Eindhoven University of Technology, with a superconducting material and a strong magnetic field. ‘The measurements of the particle at the ends of the nanowire cannot otherwise be explained than through the presence of a pair of Majorana fermions’, says Leo Kouwenhoven.

The device is made of an Indium Antemonide nanowire, covered with a Gold contact and partially covered with a Superconducting Niobium contact. The Majorana fermions are created at the end of the Nanowire. (from the TU Delft website)

At the end of the TU Delft news release, they mention more about Ettore Majorana and this is where the story gets quite intriguing,

The Italian physicist Ettore Majorana was a brilliant theorist who 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. 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-known Higgs boson. But Ettore Majorana the person is every bit as mysterious as the particle. In 1938 he 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. No trace of Majorana was ever found.

Here’s the citation for the article describing the discovery of the Majorana fermion (from the TU Delft news release),

The article is published in Science Express on 12 April: Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices, V. Mourik, K. Zuo, S.M. Frolov, S.R. Plissard, E.P.A.M. Bakkers, L.P. Kouwenhoven

There’s more information and there are more images with the April 12, 2012 TU Deflt news release.