Electrical engineers are obviously very familiar and comfortable with the basic diode, a passive and vital component that restricts current flow to one direction only, while mechanical engineers ...

Thermal diodes, much like their electrical counterparts, provide unidirectional heat transfer, allowing heat to flow in one direction while blocking it in the reverse.

And when they looked, they found that they’d made a one-way superconductor. What Ali’s group has created is very much like a diode: a component that only conducts electricity in one direction.