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Majorana fermions – the answer to Life, the Universe, and Everything?

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April 27, 2012

Majorana fermions might be the sole component of the dark matter in our Universe (Photo:

Majorana fermions might be the sole component of the dark matter in our Universe (Photo: ESO/L. Calçada)

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Physicists at the Delft University of Technology, Netherlands, have achieved a milestone that might soon revolutionize the world of quantum computing, quantum physics, and perhaps shed new light on the mystery of the dark matter in our universe. Experimenting with nanoelectronics, a group led by Prof. Leo Kouwenhoven has succeeded in detecting the elusive Majorana fermion in the laboratory, without the need for a particle accelerator.

The find is the culmination of decades of research. First theorized by Italian physicist Ettore Majorana in 1937 by building on the work of Erwin Schrödinger and Paul Dirac, the Majorana fermion emitted too weak a signal to be spotted within most materials. Recently, however, theoretical physicists have suggested that some exotic materials might circumvent defects and impurities found elsewhere and allow for the detection of this elusive particle.

Building on this knowledge, Kouwenhoven connected indium antimonide nanowires to a circuit with a gold contact at one end and a slice of superconductor at the other, and then exposed the circuit to a moderate magnetic field. Measurements of the electrical conductance of the nanowires showed a peak at zero voltage that is consistent with the formation of a pair of Majorana particles.

Conceptual close-up of the Majorana nano-device
Conceptual close-up of the Majorana nano-device

This special kind of fermion has the unique property of being its own antiparticle. An antiparticle is defined as a subatomic particle having the same mass as a given particle, but opposite electric or magnetic properties – for instance, the antiparticle of a negatively-charged electron is a positively-charged positron. The unique properties of Majorana fermions generate an interesting behavior whenever two particles interact.

Elementary particles come in two kinds: bosons, such as photons, and fermions, such as electrons. Besides having different charge and spin properties, they also behave quite differently when two particles of the same kind interact with each other.

When two bosons trade places, there is no change in their quantum mechanical state, and they become interchangeable; when two normal fermions trade places, the sign of their mathematical "wavefunction" changes from positive to negative with each switch, returning to their original state after two switches. Majorana fermions, on other hand, "remember" their previously taken path.

This property makes Majorana fermions a very strong candidate for use in quantum computers. While we've seen a number of developments in quantum computing in recent years, from qubits in semiconductors to manipulating quantum information through electrical fields, one longstanding issue is that the qubits – "quantum bits," the basic unit of information in a quantum computer – are unstable and highly sensitive to external influences.

Leo Kouwenhoven and his team in the lab
Leo Kouwenhoven and his team in the lab

Not so with this particle, which promises to be unaffected by external influences (even though, it should be pointed out, it’s not yet entirely clear whether qubits created in this manner will be long-lived enough to be used in that way).

More broadly, the "memory" of these particles could be a crucial factor that will enable researchers to more effectively crack some of the long-standing mysteries of quantum mechanics once and for all, helping to investigate the behavior of other particles.

Also, as some researchers suggest, the particles may play a crucial role in cosmology – a proposed theory assumes that the mysterious dark matter, which is thought to form around 73 percent of our Universe, is composed entirely of Majorana fermions.

The video below illustrates the process by which Kouwenhoven's team managed to isolate the fermions.

The research was published in the journal Science and was financed by the FOM Foundation and Microsoft.

Sources: Delft University of Technology, Science

About the Author
Dario Borghino Dario studied software engineering at the Polytechnic University of Turin. When he isn't writing for Gizmag he is usually traveling the world on a whim, working on an AI-guided automated trading system, or chasing his dream to become the next European thumbwrestling champion.   All articles by Dario Borghino
8 Comments

Fascinating! Watch this TED talk by Randy Powell to understand/see the math behind every phenomenon:

Also, check out his YouTube course on Vortex Math. Powerful stuff.

George Swan
27th April, 2012 @ 08:05 pm PDT

What these researchers discovered is important. But these are quasi particles (e.g. like phonons). These are not actual free element particle like the ones you get with a CERN like accelerator. Big difference.

http://en.wikipedia.org/wiki/Quasiparticle

quax
28th April, 2012 @ 10:31 pm PDT

This article has some serious problems with it.

First, and most importantly, the discovered majorana fermion is NOT a fundamental particle. What they're talking about is a quantum quasi-particle. Under certain conditions, groups of particles can behave like single particles.

These "majorana fermions" are just made up of other particles and field interactions. They have nothing to do with dark matter.

The article also says something about "when two fermions change places, their signs change". This is very , very poor research. What you're talking about is NOT fermions changing places, but the difference between a fermion and an ANTI-fermion. Nothing's changing places here.

The discovery of a new FUNDAMENTAL majorana fermion WOULD be a big discovery. It is theorized that the neutrino is, in fact, a majorana fermion. As of yet, we do not know.

htomerif
29th April, 2012 @ 02:43 am PDT

I bet Microsoft would love to be the first to come out with a quantum computer. I wounder how much they put towards quantum research?

Abodame99
29th April, 2012 @ 05:37 am PDT

re; Abodame99

Microsoft is a software firm. Apple on the other hand.

Slowburn
29th April, 2012 @ 07:54 pm PDT

If this turns out true this will have implications on computing, fusion, space travel and imaging. The understanding of the ether will dramatically change our lives as much as the understanding of the elements has changed mankind.

Matt Fletcher
30th April, 2012 @ 09:02 am PDT

@Slowburn

Any computer manufacturor could actually come out with a quantum computer once the processor developers have done their job. Apple doesn't build their own processors. Now they use Intel, earlier IBM and Motorola. But you're probably right about it not being Microsoft unless they decide to go into the hardware business full force. They do have the Xbox and a lot of periferals so who knows...

László Hágó
1st May, 2012 @ 03:48 am PDT

Another issue with this article is the poor usage of the term "dark matter". The universe is not made up of "73% dark matter". It is approx 23.3% dark matter, 72.1% dark energy - they are not the same. So perhaps the author meant to say 73% dark energy - though the intent seemed geared toward matter.

Barry Kaye
23rd May, 2012 @ 10:50 am PDT
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