After 80 years, a team of researchers may have found the first solid evidence for the Majorana fermion — a particle that is also its own antiparticle. Is the hypothetical particle hypothetical no more?
Majorana Fermion
Majorana fermion is named after Ettore Majorana, the man who, in 1937, had the brilliant idea that somewhere in the fermion family are particles that are also their own antiparticles. Majorana's hypothesis came just nine years after physicist Paul Dirac predicted that every particle in the universe has an antiparticle, a claim that was proven just a few years after.
Simply put, particles and antiparticles are in essence, identical twins with opposite charges. Now, because of their opposing charges, when a particle and an antiparticle meet, they would both be annihilated and leave a trace of energy.
It's easy to understand why the Majorana particle is unique, as it is both particle and antiparticle to itself. For 80 long years, it was a mere hypothesis, but it so happens that a team of researchers from Stanford University and University of California were able to manufacture the particle after a series of laboratory experiments.
Quasiparticle Experiments
First of all, what are quasiparticles? Quasiparticles are particle-like excitations that come about from the behavior of electrons in response to superconductive materials. While they are not naturally occurring in nature, they can be regarded as virtual particles or real Majorana particles.
In their series of experiments, the team from UC-Davis and UCLA stacked superconductor and magnetic topological insulator films together with the former on top, while the UC-Irvine and UCLA groups performed the transport measurements. What they did was to send an electrical current through the stack while inside a chilled vacuum chamber. Electrons then cruised along either side of the films.
Taking it a step further, Stanford physics professor Shoucheng Zhang proposed adding a magnetic material to the topological insulator, making the electrons flow in opposite directions. When they swept a magnet over the stack, the electrons switch directions. At some points, Majorana particles emerged from the stack and slowed down enough for researchers to study and observe them.
Angel Particle In The Universe
With these results, Stanford physics Professor Giorgio Gratta, who wasn't involved in the study states that while what the team was able to create were artificially made, there is really no saying whether or not these particles can naturally occur in the universe.
Further, if Majorana particles are found to be neutrinos, which are also believed to be their own antiparticle, then it's possible that the whole universe is actually filled with them. He also stresses that even if they are not the same, there could still be something to be learned from one to understand the other.
In the future, Zhang believes that these findings could be used to create quantum computers. For now, Professor Zhang has suggested calling the chiral Majorana fermion the "angel particle," referring to the Dam Brown novel Angels and Demons, which involved a bomb utilizing the power of matter-antimatter annihilation.
The team's findings are published in the journal Science.
