In a discovery that concludes an 80-year quest, Stanford and University of California researchers found evidence of particles that are their own antiparticles. These ’Majorana fermions’ could one day help make quantum computers more robust.
In 1928, physicist Paul Dirac made the stunning prediction that every fundamental particle in the universe has an antiparticle – its identical twin but with opposite charge. When particle and antiparticle met they would be annihilated, releasing a poof of energy. Sure enough, a few years later the first antimatter particle – the electron’s opposite, the positron – was discovered, and antimatter quickly became part of popular culture.
But in 1937, another brilliant physicist, Ettore Majorana, introduced a new twist: He predicted that in the class of particles known as fermions, which includes the proton, neutron, electron, neutrino and quark, there should be particles that are their own antiparticles.
Now a team including Stanford scientists says it has found the first firm evidence of such a Majorana fermion. It was discovered in a series of lab experiments on exotic materials at the University of California in collaboration with Stanford University. The team was led by UC-Irvine Associate Professor Jing Xia and UCLA Professor Kang Wang, and followed a plan proposed by Shoucheng Zhang, professor of physics at Stanford, and colleagues. The team reported the results July 20 in Science.
“Our team predicted exactly where to find the Majorana fermion and what to look for as its ‘smoking gun’ experimental signature,” said Zhang, a theoretical physicist and one of the senior authors of the research paper. “This discovery concludes one of the most intensive searches in fundamental physics, which spanned exactly 80 years.”