Majorana fermions — particles that are their own antiparticles — have never been observed in the context of high-energy physics in which they were originally proposed, but have been realized as quasiparticles in condensed-matter systems. Being able to study such quasiparticles in different materials is useful to fully characterize them and to learn how to manipulate them: an Fe-based superconductor can now be added to the list of systems in which Majorana quasiparticles have been observed, as Dong-Lai Feng, Tong Zhang, Zhi-Ping Yin and colleagues report in Physical Review X.

Majorana bound states, also called Majorana zero modes (MZMs), are attracting considerable attention because they do not behave as fermions or bosons — the two types of elementary particles that make up matter and light — but as a special type of particle, anyons. Anyons only exist in 2D systems and have the exotic ability to encode quantum information. MZMs are thus potentially useful as qubits for quantum computers. Because MZMs are topological in nature and thus robust against perturbations, a quantum computer based on them would have the advantage of being error protected.