Single- and two-qubit quantum gates using superimposed optical lattice   potentials
  Steps towards implementing a collision based two-qubit gate in optical lattices have previously been realized by the parallel merging all pairs of atoms in a periodicity two superlattice. In contrast, we propose an architecture which allows for the merger of a selected qubit pair in a novel long-periodicity superlattice structure consisting of two optical lattices with close-lying periodicity. We numerically optimize the gate time and fidelity, including the effects on neighboring atoms, and in the presence of experimental sources of error. Furthermore, the superlattice architecture induces a differential hyperfine shift, allowing for single-qubit gates. The fastest possible single-qubit gate times, given a maximal tolerable rotation error on the remaining atoms at various values of the lattice wavelengths, are identified. We find that robust single- and two-qubit gates with gate times of a few 100~$\mu$s and with error probabilities $\sim{}10^{-3}$ are possible. 
Nils B. J{\o}rgensen, Mark G. Bason, Jacob F. Sherson
quant-ph cond-mat.quant-gas