  Ultracold atoms in optical lattices are an important platform for quantum
information science, lending itself naturally to quantum simulation of
many-body physics and providing a possible path towards a scalable quantum
computer. To realize its full potential, atoms at individual lattice sites must
be accessible to quantum control and measurement. This challenge has so far
been met with a combination of high-resolution microscopes and resonance
addressing that have enabled both site-resolved imaging and spin-flips. Here we
show that methods borrowed from the field of inhomogeneous control can greatly
increase the performance of resonance addressing in optical lattices, allowing
us to target arbitrary single-qubit gates on desired sites, with minimal
crosstalk to neighboring sites and greatly improved robustness against
uncertainty in the lattice position. We further demonstrate the simultaneous
implementation of different gates at adjacent sites with a single global
control waveform. Coherence is verified through two-pulse Ramsey interrogation,
and randomized benchmarking is used to measure an average gate fidelity of
~95%. Our control-based approach to reduce crosstalk and increase robustness is
broadly applicable in optical lattices irrespective of geometry, and may be
useful also on other platforms for quantum information processing, such as ion
traps and nitrogen-vacancy centers in diamond.
