In 1937, Italian physicist Ettore Majorana raised the idea of a fermion that is its own antiparticle, which has since become known as the Majorana fermion. Now, a collaborative effort from the University of Sydney and Microsoft has demonstrated how these particles might be used to help push forward the field of quantum computing.
Researchers have observed electrons behaving as Majorana fermions, having taken on the form of quasiparticles. The electrons were moving down a length of nanowire, and were subjected to a magnetic field. In normal circumstances, an electron’s quantum state of spin doesn’t correspond with its motion — but in this case, the spin and the motion did align.
As a result, electrons with opposing spins would also perform opposing helical twists as they moved along the nanowire. This behavior is not unlike the two-dimensional quasiparticles that can be used in a topological quantum computer, which uses spin to hold onto information rather than an electrical charge.
A topological quantum computer uses a different principle than the common trapped ions approach. Two quasiparticles form a “braid” where they maneuver around one another across two spatial dimensions and one time dimension.
It’s thought that this could provide a much more stable foundation for the superposition that facilitates quantum calculations. While a great deal of progress has been made with trapped ions in recent years, it’s still difficult to maintain superposition reliably, so research into other solutions continues.
This study into Majorana fermions could potentially offer up new avenues for the development of a topological quantum computer — even though a fully functional implementation of such a device is still a long way off.