There is a delicate symmetry in the world of particle physics. For every particle, there is an antiparticle of the same mass but opposite charge. Antimatter is not just the stuff of science fiction- it is a very real thing, but we can’t run across it when out for a walk. When a particle and its antiparticle meet, they annihilate, releasing photons. Due to CP violation (which we discussed a few years ago), we have an abundance of matter in the universe, but little antimatter.
But what if I told you there was a particle that spit on that symmetry? A particle that is its own antiparticle.
Galleons, meet the Majorana fermion.
Back in the 1930s, a physicist by the name of Ettore (you guessed it) Majorana1 predicted that quantum theory allowed for a special little fermion that hovered right on the border between matter and antimatter, making that single fermion its own particle-antiparticle pair.
Over the years, most predicted particles have been found. Noted exceptions are the attention-whore Higgs boson and the quieter Majorana fermion.
Well, looks like we can check the Majorana fermion off the list, dear galleons, because a group of scientists at TU Delft’s Kavli Institute and the Foundation for Fundamental Research on Matter have found it. Led by nanoscientist Leo Kouwenhoven, the scientists created a rather unique way of finding the elusive Majorana fermion. See, we usually detect particles by smashing beams of protons or protons/anti-protons or what-have-you together in supercolliders. The resulting particle spray hits the detectors and is analyzed for anomalies, which leads to the discovery of new particles. But even the LHC, beast though it may be, isn’t quite sensitive enough to detect the super-elusive Majorana. However, our scientists realized there was another solution: nanostructures.
Kouwenhoven and his team created a nanoscale electrical device out of indium antemonide nanowire, superconducting niobium contact, and a strong magnetic field:
Two particles appeared at either end of the device, particles that the team says can only be Majorana fermions. I’m going to trust them, because I’m too tired to slog through the technical specs of the experiment (maybe I’ll get around to it later- if so, I’ll update you with more information on the hows and whys of the Majorana detection).
Beyond the fact that they are interesting and unique particle specimens, Majorana particles are special for a few other reasons. There’s a theory that suggests that dark matter, that unknown quantity in our universe, is comprised of Majorana fermions (though it’s by no means the only, or even most popular, theory surrounding dark matter composition). What’s even more tantalizing about the Majorana fermion is the potential for use in quantum computing. A quantum computer based on Majorana fermions, due to their unique nature, is far more stable than your average quantum computer. It would be quite exciting if the stability of the Majorana fermion helped us move quantum computing out of the realm of theory and into the realm of reality.
Regardless, new particle.
Exciting stuff, my galleons.