Imaging single atoms in a three-dimensional array

Asingle neutral atom trapped by light is a promising qubit. It has weak, well-understood interactions with the environment, its internal state can be precisely manipulated, interactions that entangle atoms can be varied from negligible to strong and many single atoms can be trapped near each other in an optical lattice. This collection of features would allow for a relatively large quantum computer if each neutral atom qubit could be independently detected and addressed. A quantum computer with even 50 qubits would allow quantum simulations that are out of the reach of classical computers. So far, fewer than ten single atoms have been simultaneously imaged. Here we demonstrate trapping and imaging of 250 single atoms in a three-dimensional optical lattice and show that imaging is highly unlikely to change the pattern of site occupancy. Our lattice spacing is large enough that, in principle, individual atoms can be addressed, which in combination with reproducible imaging should allow for verifiable filling of vacancies, execution of site-specific quantum gates and measurement of each atoms final quantum state. The lattice we use can readily be scaled to include thousands of trapped atoms.