A Majorana Glimpse...

Scanning-tunnelling-microscope image showing a chain of iron atoms. The inset shows the probability that Majorana quasiparticles reside in that portion of the chain. The dark red blob at the tip indicates high probability at the tip. (Courtesy: Yazdani Lab, Princeton University)

The strongest evidence yet that Majorana quasiparticles (MQPs) can be found lurking in some solids has been unveiled by physicists in the US. The team used a scanning tunnelling microscope (STM) to locate MQPs at the ends of atomic chains of magnetic iron lying on the surface of a lead superconductor. MQPs have special properties that could make them ideal for use in quantum computers, and this latest breakthrough could lead to practical devices that make use of the quasiparticles.

First predicted by the Italian physicist Ettore Majorana in 1937, the Majorana fermion has zero charge and is its own antiparticle. Unlike conventional fermions such as the electron – which obey Fermi–Dirac statistics – the Majorana fermion obeys "non-Abelian" statistics. This means that quantum information encoded in the particles would be highly resistant to decoherence. Decoherence is the bane of physicists who are trying to develop practical quantum computers, and therefore devices based on Majorana fermions could be used in future quantum-information systems.

Physics World: Majorana quasiparticles glimpsed in magnetic chains
Hamish Johnston, editor of physicsworld.com

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