Programmable atomic systems offer a powerful route to quantum simulation of strongly correlated many-body dynamics beyond the reach of classical computation. As an introductory example, I will briefly discuss implementations of lattice gauge theories, where atomic, ionic, and Rydberg platforms enable controlled studies of gauge-invariant dynamics, constrained Hilbert spaces, string formation and string breaking, and real-time non-equilibrium phenomena. The main part of the talk addresses two central questions that arise as these systems scale: How do we trust what the device is doing? and how can we use it to actively design new quantum matter? I will discuss bounded-error quantum simulation, combining experimental data with Hamiltonian and Lindbladian learning to place quantitative confidence bounds on implemented dynamics and observables, and inverse quantum simulation, where programmable devices serve as machine-learning–assisted design engines to identify many-body states with desired properties and reconstruct Hamiltonians that realize them. I will conclude with two outlooks toward future programmable quantum technologies: quantum sensing networks, where entangled atomic ensembles can implement non-local Ramsey interferometry to probe the gravity–quantum interface, and ion tweezers as a scalable architecture for quantum computing.