Fabio Beltram

A switch that knows which way to let current flow. That's how a Josephson diode works — a superconducting bridge where current goes willingly in one direction but meets resistance in the other. In the new study, such a bridge was made from graphene — a sheet of carbon just one atom thick.

A Stradivarius violin can only be made from wood that grew under special conditions. For a long time, it was believed that graphene for delicate quantum effects had to be exfoliated from graphite with tape, and that a crystal grown in a test tube was incapable of such feats. This work shows that graphene grown from a gas mixture can sound like a Stradivarius.