An international team of researchers has fashioned a device from nanowires that may finally prove the existence of long-theorized quasiparticles known as Majorana particles. Once these Majorana particles are identified and isolated, they could form the basis of a quantum bit—or qubit—that would process information in a new kind of quantum computer with improved stability.
Ever since 1937, when the Italian physicist Ettore Majorana first theorized the existence of the quasiparticle that takes his name, there has been much effort to prove that it really exists, with little to show for it. But this changed back in 2012, when researchers at Delft University of Technology (TU Delft) in the Netherlands saw strong hints of Majoranas when they sent electrons into a semiconducting nanowire placed alongside superconducting material.
Since that 2012 Delft research, there have been a number of experiments that have reported evidence of Majoranas in a similar system. However, all of those experiments, including the original one at Delft, left open the possibility of alternative explanations for the results. So, unil now, there has been no “smoking-gun” evidence of Majoranas, said Hao Zhang, a post-doc at TU Delft, in an e-mail interview with IEEE Spectrum.
There remained one definitive way to prove the existence of these Majorana particles and that was for them to exchange places along the nanowire, a phenomenon referred to as exchanging statistics of the particles. These statistics describe how the quantum mechanics of the system change when two indistinguishable particles switch places.
This exchange of places along the nanowire is also called “braiding”. These braids form the logic gates of topological quantum computers. However, no one could see how this braiding was possible because the act of getting the particles to pass each other in this nanowire would annihilate them.
If this braiding of these quasiparticles could somehow be artificially induced, researchers theorized, it would result in a far more stable method for quantum computing than employing trapped quantum particles. That’s because the system wouldn’t be susceptible to outside influences like thermal fluctuations.
In research described in the journal Nature, the researchers, from TU Delft, Eindhoven University of Technology in the Netherlands, and the University of California, Santa Barbara, created a hashtag-like device made from…