  Assembling and maintaining large arrays of individually addressable atoms is
a key requirement for continued scaling of neutral-atom-based quantum computers
and simulators. In this work, we demonstrate a new paradigm for assembly of
atomic arrays, based on a synergistic combination of optical tweezers and
cavity-enhanced optical lattices, and the incremental filling of a target array
from a repetitively filled reservoir. In this protocol, the tweezers provide
microscopic rearrangement of atoms, while the cavity-enhanced lattices enable
the creation of large numbers of optical traps with sufficient depth for rapid
low-loss imaging of atoms. We apply this protocol to demonstrate
near-deterministic filling (99% per-site occupancy) of 1225-site arrays of
optical traps. Because the reservoir is repeatedly filled with fresh atoms, the
array can be maintained in a filled state indefinitely. We anticipate that this
protocol will be compatible with mid-circuit reloading of atoms into a quantum
processor, which will be a key capability for running large-scale
error-corrected quantum computations whose durations exceed the lifetime of a
single atom in the system.
