  Trapped neutral atoms have become a prominent platform for quantum science,
where entanglement fidelity records have been set using highly-excited Rydberg
states. However, controlled two-qubit entanglement generation has so far been
limited to alkali species, leaving the exploitation of more complex electronic
structures as an open frontier that could lead to improved fidelities and
fundamentally different applications such as quantum-enhanced optical clocks.
Here we demonstrate a novel approach utilizing the two-valence electron
structure of individual alkaline-earth Rydberg atoms. We find fidelities for
Rydberg state detection, single-atom Rabi operations, and two-atom entanglement
surpassing previously published values. Our results pave the way for novel
applications, including programmable quantum metrology and hybrid atom-ion
systems, and set the stage for alkaline-earth based quantum computing
architectures.
