Single rare-earth ions are hard to observe and even harder to use as qubits. However, with the help of coupling to an optical cavity and clever engineering of selection rules, a big step has been taken to establish their new role in the quantum world.

中文翻译：

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难得的量子飞跃

单个稀土离子很难观察，甚至更难以用作量子比特。但是，借助于耦合到光腔和巧妙设计选择规则，迈出了一大步，确立了它们在量子世界中的新作用。