April 15, 2012
Scientists Say They’ve Found The Elusive Majorana Fermion
After a search that has lasted roughly three-quarters of a century, researchers believe they have at long last discovered evidence of an elusive particle that could be its own anti-particle.
The existence of the particle, which is known as the Majorana fermion, was first predicted some 75 years ago, according to BBC News Science Correspondent Jonathan Amos. Now, a team of Dutch scientists believe that they have created an electronic device small enough to test for the Majorana, and they believe that their results suggest that it does, in fact, actually exist.
The researchers have "produced quasiparticles that act like Majorana fermions: electrically-neutral particles that are their own antiparticles, such that if two collide, they annihilate," Matthew Francis of ArsTechnica wrote on Thursday. The pair of zero-velocity quasiparticles was discovered by constructing a very thin wire known as a nanowire that was created from semiconductor materials and then connected to a superconductor, he said.
Leo Kouwenhoven headed up a group of scientists from the Delft University of Technology, who teamed with colleagues from Eindhoven University of Technology to create "a nanoscale electronic device" consisting of "an extremely small nanowire“¦ a superconducting material and a strong magnetic field." In that device, a pair of Majorana fermions appeared at both ends of the nanowire, Kouwenhoven's university said in an April 12 statement.
"The measurements of the particle at the ends of the nanowire cannot otherwise be explained than through the presence of a pair of Majorana fermions," Kouwenhoven said.
Majorana fermions, which are particles that essentially straddle the line between matter and ant-matter, were first discovered by Italian physicist Ettore Majorana in the late 1930s. Their discovery is "very interesting," Delft University said, not only because of what it means to physics but also the possible implications in the study of cosmology and, specifically, the search for what is known as dark matter throughout the universe.
"The results don't provide a direct detection of Majorana fermions," said Robert F. Service of ScienceNow. However, he added, "if Majoranas are confirmed, they are expected to have properties that make them ideal for constructing a quantum computer. When you move two Majorana fermions with respect to one another, they essentially 'remember' their former position, a property that could be used to encode data at the quantum level. Kouwenhoven's group hasn't spotted that signature yet, but they're on the hunt now."
Kouwenhoven's team published their findings in the journal Science on April 12.
Image Caption: The device is made of an indium antemonide nanowire, covered with a gold contact and partially covered with a superconducting niobium contact. The Majorana fermions are created at the end of the nanowire. (Credit: Copyright TU Delft 2012)