Bizarre theoretical particle could finally pave the way for superfast quantum computers
The first of a certain kind of quantum computers might be created from a particle with a strange property that has never been seen.
Researchers from the University of Sydney and Microsoft studied electrons ‘swirling’ down a wire, and in doing so have provided further evidence for a mysterious kind of quasiparticle – a particle that is not really there, but is formed from the collective movement of other particles.
In a paper published in Nature Communications, researchers from the University of Sydney describe how the electrons formed a quasiparticle under certain conditions. These quasiparticles act as theoretical objects called Majorana fermions.
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The reason this is important is that it is widely thought Majorana particles might turn out to be the ideal way to carry information in specific quantum computers, known as topological quantum computers. These use the movements of particles through 2D space as the qubit, which means they would be much more robust than other forms of quantum computers. However, development of topological quantum computers is lagging behind other kinds, which use the spin of ions held in traps or electrons in semiconductors.
One step towards a topological quantum computer is finding a Majorana particle.
What is a quasiparticle?
When a particle of matter meets its antimatter particle, they annihilate each other. Majorana particles act like their own antiparticle because, it is thought, when they come together they annihilate themselves.
The particles were first proposed in 1937, and in 2010 research suggested a pair of Majorana fermions could form at the boundary between a superconductor and a semiconducting nanowire in a magnetic field. Then, in 2012, Leo Kouwenhoven at Delft University of Technology in the Netherlands, revealed the most promising evidence yet, but it was still not enough to be called a discovery.
“When Majorana fermions were first shown to exist in 2012, there were many who said there could be other explanations for the findings,” said Dr Maja Cassidy, co-author of the new paper.
Professor Leo Kouwenhoven, author of the 2012 paper, now leads Microsoft’s Station Q in the Netherlands. After the paper came out, he challenged others to prove Majorana particles were behind the observations.
The new paper does this by showing the electrons in the semiconducting nanowire have a certain property; their quantum spin is opposite to their momentum inside a magnetic field.
“This information is consistent with previous reports observing Majorana fermions in these nanowires,” Dr Cassidy said.
“Here at Station Q Sydney we are building the next generation of devices that will use quasiparticles known as Majorana fermions as the basis for quantum computers.”