Metrology and many-body physics with strontium in a 2D tweezer array*

Arrays of neutral atoms trapped in optical tweezers are a powerful platform for single-particle-controlled quantum gas assembly, entanglement generation, and many-body physics. Alkaline-earth atoms, such as strontium, offer a rich singlet-triplet electronic structure which enhances the capabilities of tweezer arrays---principally via high-fidelity low-loss imaging and ultra-narrow `clock' transitions with direct applications in metrology and quantum information science. Indeed, our tweezer array clock establishes a new, state-of-the-art platform for comparisons of atomic ensembles' clock frequencies. Now, we are working to introduce off-resonant Rydberg excitation---Rydberg dressing---of the clock state introduces strong long-range interactions between atoms in a low-entropy two-dimensional array. The resulting transverse field Ising Hamiltonian enables spin-squeezing on the clock transition, leveraging quantum entanglement for improved metrological sensitivity. This also offers a rich many-body system in which entanglement may propagate beyond the range of the underlying interactions. These goals demonstrate the power and versatility of combining controllable long-range interactions with single particle manipulation of highly coherent quantum systems.