The spotlight materials for quantum computers are usually the photogenic ones — the golden chandeliers of superconducting circuits, the shimmering chips cooled to near absolute zero, or the trapped ions dancing in vacuum chambers. But the spotlight has now shifted with China’s new export restrictions on rare-earth minerals — and the United States’ swift reaction to those restrictions that sent markets in a free fall last week. If you’re like me and the first thing you think about when you hear “rare earth” is the classic rock, R&B-rooted Detroit band from the 1970s, it may be a surprise that behind all those chandeliers and futuristic chips lies a quieter foundation of rare-earth elements. Most rare-earth elements — the lanthanides — get their quantum usefulness from a hidden layer of electrons, known to chemists as the 4f shell, tucked deep inside the atom and shielded from interference.

Full report : Quantum computing needs rare earth magnets which China dominates.