Third research team close to creating Majorana fermion

Mar 16, 2012 by Bob Yirka report

(PhysOrg.com) -- Recently there has been a virtual explosion of research efforts aimed at creating the elusive Majorana fermion with different groups claiming to be near to creating them. First there was news that a team at Stanford was on the precipice, then came reports that another group at Delft University of Technology in The Netherlands was very close as well. Now comes news of yet another team who some think may have the best chance yet of making them, and better yet, using them to help make quantum computing possible. This third group, made up of Chinese and American teams takes the approach, as they describe in their paper published in Science, of growing a topical insulator film on top of a superconductor.

A fermion is a particle that adheres to the Fermi-Dirac statistics - as opposed to a . A Majorana fermion specifically, is a fermion particle pairing that is its own anti-particle, and was first proposed by Ettore Majorana back in 1937. To make a Majorana fermion, a particle and its anti-particle must be combined into a single new particle.

In similar fashion, as a result of the way some crystals are grown there can exist conducting electrons and so-called mobile holes, which are akin to electron anti-particles. They form when an electron moves out of the . If a conducting electron falls into such a hole, it disappears, much the same way particles and anti-particles obliterate one another if they happen to meet. Thus, creating a Majorana fermion has been a significant problem.

To create an environment where electrons and holes could co-exist, researchers have been using paired with topological insulators, or substances that only on their surfaces. When the topological is made to meet with the superconductor, the electrical field creates a boundary that prevents the from falling into the holes and disappearing. Under such conditions, Majorana fermions should be able to form.

In this latest effort, the research team has coated a superconductor with a topological insulator, creating an ultra smooth juncture between the two. The resulting conditions, the researchers believe, should be optimal for the creation of Majorana fermions. And though they haven’t as yet spotted any, they believe they are very close. If they do spot them, they believe that by applying an they should be able to control them. And if that happens, they just might be able to use them as qubits in a quantum computer.

Using Majorana fermions instead of quantum bits in a quantum computer is considered to be preferable because they are considered to be more robust.

It’s still not known at this time if any of the three research efforts will prove fruitful, and if so, which will win out over the others, but it appears clear that the seventy five year search for a way to create Majorana fermions may at long last result in success.

Explore further: CERN makes public first data of LHC experiments

More information: The Coexistence of Superconductivity and Topological Order in the Bi2Se3 Thin Films, Science DOI: 10.1126/science.1216466 (ArXiv preprint)

ABSTRACT
Three-dimensional topological insulators (TIs) are characterized by their nontrivial surface states in which electrons have their spin locked at a right angle to their momentum under the protection of time reversal symmetry. The topologically ordered phase in TIs does not break any symmetry. The interplay between topological order and symmetry breaking such as observed in superconductivity can lead to new quantum phenomena and devices. We fabricate a superconducting TI/Superconductor (SC) heterostructure by growing Bi2Se3 thin films on superconductor NbSe2 substrate. Using scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we observed the superconducting gap at Bi2Se3 surface in the regime of Bi2Se3 film thickness where topological surface states form. This observation lays the groundwork for experimentally realizing Majorana fermions in condensed matter physics.

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Callippo
1 / 5 (6) Mar 17, 2012
A Majorana fermion specifically, is a fermion particle pairing that is its own anti-particle
These guys apparently forget that the Cooper pairs are known for years.. The fact when physicists are looking (and spending money) for notoriously known things is not so exceptional in the contemporary physics, which faces a huge overemployment.
antialias_physorg
5 / 5 (6) Mar 17, 2012
Cooper pairs are pairs of electrons. Electrons have a charge.
Majorana fermions are their own antiparticles - so they cannot have a charge.

An antiparticle to a charged particle would have opposite charge - so it is not the same as its antiparticle and hence no Majorana fermion.

The fact when physicists are looking (and spending money) for notoriously known things is not so exceptional in the contemporary physics

The fact that you don't know diddly squat about physics (or can't even be arsed to google) is not so exceptional - you keep demonstrating it at every turn.
Shelgeyr
1 / 5 (1) Mar 17, 2012
Its still not known at this time if any of the three research efforts will prove fruitful, and if so, which will win out over the others...


OK, so how the heck do they justify using the word "close" in the headline? How do they, or even could they, know if they're "close" or not, until they succeed. If they do.

Tell you what... If the day comes when one of the teams actually succeeds, THEN they can look back and say "You know what? LAST week we were close to creating the Majorana fermion."

This article is just more "keeping the fires stoked" hype.

I blame the author, however, so good luck to the teams. And I genuinely mean that. Good luck, people! Or rather, since I'm fairly certain quantum physicists don't believe in luck (and neither do I), better to simply say "I wish you all success".
Callippo
1 / 5 (2) Mar 17, 2012
Majorana fermions are their own antiparticles - so they cannot have a charge..
Try to explain, after then, how they do want to create a Majorana fermions just from electrons in the above article?
Callippo
1 / 5 (2) Mar 17, 2012
To preserve an electron-hole pairing, physicists are trying to combine superconductors with materials known as topological insulators, which conduct electricity only on their surface. When joined, the two materials create a pattern of electric fields at their boundary which can stop electrons from falling into holes, potentially allowing Majorana fermions to form.
daywalk3r
3.1 / 5 (15) Mar 19, 2012
Electron "holes" are no real particles, so even if the team succeeds and manages to suppress electron/hole recombination at the SC/TI boundary, it will still be just a
Quasi-majorano (the uglier brother of Quasi-modo) ;-D

Kind of like a wolf/glasswall/sheep analogy, where the wolf is the hole, the glass wall is the barrier at the boundary, and the poor sheep is the electron. Wolf bashing his head against the invisible wall to get a piece of sheep, but ain't gonna happen :-P
Now just need to find a reason why sheep would want to hug wolf too. Lets just assume sheep had a bad day and is desperately suicidive. And at the end of the day, wolf is still hungry & the sheep still desperate - No free lunch ;-/

But even then, the separation distance between the constituents of the quasi-stable quasi-majorano fermions might turn out to be too big to allow for much useful interactions/correlations, thus sort of crushing the fancy qubit plans.

We will see.. (said the blind man to the deaf man)
daywalk3r
3.3 / 5 (14) Mar 19, 2012
oh, and almost forgot..
since I'm fairly certain quantum physicists don't believe in luck
Thanks for the laugh, Shelgeyr :-)

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