The way we do research is reminiscent of the timeless show “Fraggle Rock”. In the world of fraggles, there are fraggles, which mostly go about their silly business. And there are also doozers. Those are creatures that are focused, motivated and constantly building beautiful scaffolding of some transparent substance. They fill space with this scaffolding in no time. The twist is, that this scaffolding is very tasty, and fraggles love it – so they just grab it and eat it. In one episode fraggles start feeling bad about destroying the magnificent scaffolding castles built by doozers, so they stop doing it. This makes doozers very upset, because as it turns out, they enjoy making fraggles happy, and want their structures to be eaten.

In our research we work and fully depend on material scientists who grow magnificent structures, such as semiconductor nanowires. Growing nanowires is science with a twist of magic, because a lot of it is about methodical yet creative tuning of growth parameters that produces qualitatively new classes of materials. In a recent example, I was fortunate to collaborate with material scientists from Eindhoven on the characterization of a new type of nanostructure they produced – a semiconductor nanocross.

These crystals come about when two nanowires grow into each other. The Eindhoven group have achieved a high degree of control and reproducibility in producing these nanocrosses out of InSb. Our experimental team in Delft then contacted all four legs of a cross with metals and superconductors and found them to be of high electronic mobility and in the quasi-ballistic transport regime. Nanocrosses can find applications in research on Majorana fermions and topological quantum computing. Qubits based on Majorana fermions consist of several Majoranas, and to change the qubit state one has to switch Majorana positions. A recent theory found that this cannot be done in a single nanowire, and at least a nanowire T-junction, or a cross, is required.