In the past five years, neutral atoms have emerged as dark horse candidates in the race to build a quantum computer, a machine that would exploit the laws of quantum physics to solve certain important computational problems far more efficiently than any conventional computer.

In a neutral-atom quantum processor, atoms are suspended in ultrahigh vacuum by arrays of tightly focused laser beams called optical tweezers. Researchers have scaled up to arrays of more than 100 alkali atoms, each of which has one valence electron, and executed quantum algorithms using smaller arrays. Now they’re exploring new quantum information-processing and measurement capabilities in arrays of atoms with two valence electrons, including the alkaline-earth atoms in the second column of the periodic table and a few others with similar properties, such as ytterbium.

Tweezer arrays of alkaline-earth atoms have shown promise in both quantum computing and precision timekeeping—they can encode new kinds of qubits with long coherence times and serve as state-of-the-art atomic clocks. In the future, they may help researchers implement protocols for fault-tolerant quantum error correction and harness quantum entanglement on a large scale to further push the limits of atomic clock performance.

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