The symmetry of vanadium’s crystal structure acts as a switch for hydrogen’s quantum behavior.

Inside a vanadium crystal, hydrogen can travel in two very different ways. It may move as a conventional particle that needs enough energy to jump between locations, or behave like a quantum wave that passes through barriers. Researchers have now identified the structural change that determines which route it takes.

The finding could matter as demand grows for materials that can safely store and transport hydrogen as a source of cleaner energy. Vanadium is a promising candidate because it absorbs hydrogen readily and allows the atoms to move through its crystal lattice, although the reason for their changing behavior had remained uncertain.