We demonstrate a set of tools for microscopic control of neutral strontium atoms. We report single-atom loading into an array of sub-wavelength scale optical tweezers, light-shift free control of a narrow-linewidth optical transition, three-dimensional ground-state cooling, and high-fidelity nondestructive imaging of single atoms on sub-wavelength spatial scales. Extending the microscopic control currently achievable in single-valence-electron atoms to species with more complex internal structure, like strontium, unlocks a wealth of opportunities in quantum information science, including tweezer-based metrology, new quantum computing architectures, and new paths to low-entropy many-body physics.

The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology [1], simulation [2], and information [3]. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms [4][5][6] while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fidelity state preparation, site-resolved readout, and preservation of atomic coherence. With this approach, we achieve trapping and optical clock excited-state lifetimes exceeding 40 seconds in ensembles of approximately 150 atoms. This leads to half-minute-scale atomic coherence on an optical clock transition, corresponding to quality factors well in excess of 10 16 . These coherence times and atom numbers reduce the effect of quantum projection noise to a level that is on par with leading atomic systems [7,8], yielding a relative fractional frequency stability of 5.2(3) × 10 −17 (τ /s) −1/2 for synchronous clock comparisons between sub-ensembles within the tweezer array. When further combined with the microscopic control and readout available in this system, these results pave the way towards long-lived engineered entanglement on an optical clock transition [9] in tailored atom arrays.

Coherent control of high-quality-factor optical transitions in atoms has revolutionized precision frequency metrology. Leading optical atomic clocks rely on the interrogation of such transitions in either single ions or ensembles of neutral atoms to stabilize a laser frequency at high precision and accuracy. In addition to absolute time-keeping, the precision and coherence afforded by these transitions has enabled observations of gravitational time dilation on short length-scales, and facilitated applications in quantum information. Here, we demonstrate a new platform for interrogation and control of an optical clock transition based on arrays of individual strontium atoms held within optical tweezers that combines key strengths of these two leading approaches. We report coherence times of 3.4 seconds, record single-ensemble duty cycles up to 96% through repeated interrogation, and 4.7 × 10 −16 (τ /s) −1/2 frequency stability commensurate with present-day leading platforms. These results establish optical tweezer arrays, and their associated capacity for microscopic control of neutral atoms, as a powerful tool for coherent control of optical transitions for metrology and quantum information science.