New clues to the existence of qubit candidate Majorana

Researchers from QuTech and Microsoft in Delft and Eindhoven University of Technology have found new indications for the existence of the Majorana quasi-particle. This brings the use of this quasi-particle for a quantum computer a step closer.

The scientists used an experimental quantum chip for the measurements that indicate the existence of Majorana quasiparticles. The outcome of those measurements, a so-called zero-bias peak, contained much less noise than in experiments in 2012, when the first clues to the Majorana quasid particle were found. In addition, the height of the zero-bias peak was exactly as the theory predicts. “This is an important indication that it is indeed a Majorana,” says Leo Kouwenhoven, quantum researcher at Microsoft.

Kouwenhoven and his team at Microsoft and QuTech consider Majorana quasiparticles suitable candidates for qubits, the building blocks for a quantum computer. They are experimenting with chips with a grid of a kind of nanohashtags of semiconducting nanowires with a superconducting layer and two supposed Majoranas superimposed at the ends. At certain electric and magnetic fields, the researchers observe zero-bias peaks, the hallmark for the presence of Majoranas.

The definitive proof of the quasiparticles should follow from the swapping of the two Majoranas at the intersections of the hashtags. That would immediately be another important step towards topological qubits, which, unlike competing qubits, are stable and relatively resistant to external influences. When two Majoranas switch places, information about that switch remains, a consequence of the fact that a Majorana is its own antiparticle. Microsoft hopes to be able to base the first quantum computer on these topological qubits.

Scientists from QuTech, TU Delft, JQI in Maryland, Microsoft, Eindhoven University of Technology and UC Santa Barbara collaborated on the research.