Majoranas in semiconductor nanowires

Leo Kouwenhoven, QuTech, TU Delft

Majoranas can emerge as robust quasi-particles in properly engineered electronics devices. The needed ingredients include low-dimensional semiconductors with strong spin-orbit interaction and superconductivity. Within appropriate ranges of magnetic field and chemical potential a spin-less and charge-less quantum state emerges that is firmly pinned at zero energy. This zero energy state has all the experimental signatures of a Majorana bound state. Majoranas become particularly interesting when we can operate them as qubits since these are expected to be protected against many noise sources. This protection has a topological origin which persists as long as the global parity (i.e. even or odd total particle number) in the sample remains fixed. Current research is developing superconducting circuits that allow for Majorana qubit operations. These operations involve braiding Majoranas, or exchanging pairs of Majoranas, which should demonstrate that their quantum statistics is non-Abelian.