Stephan Plugge, Asbjørn Rasmussen, Reinhold Egger, Karsten Flensberg


Quantum information protected by the topology of the storage medium is expected to exhibit long coherence times. Another attractive feature are topologically protected gates generated through braiding of Majorana bound states. However, braiding requires branched structures which have inherent difficulties in the semiconductor-superconductor heterostructures now believed to host Majorana bound states. Here, we construct quantum bits taking advantage of the topological protection and non-local properties of Majorana bound states in a network of parallel wires. The elementary unit is made from three topological wires, two wires coupled by a trivial superconductor and the third acting as an interference arm. Coulomb blockade of the combined wires spawns a fractionalized spin, non-locally addressable by quantum dots used for single-qubit readout, initialization, and manipulation. We describe how the same tools allow for measurement-based implementation of the Clifford gates, in total making the architecture universal. Proof-of-principle demonstration of topologically protected qubits using existing techniques is therefore within reach.