Arbitrary accuracy iterative phase estimation algorithm as a two qubit   benchmark
  We discuss the implementation of an iterative quantum phase estimation algorithm, with a single ancillary qubit. We suggest using this algorithm as a benchmark for multi-qubit implementations. Furthermore we describe in detail the smallest possible realization, using only two qubits, and exemplify with a superconducting circuit. We discuss the robustness of the algorithm in the presence of gate errors, and show that 7 bits of precision is obtainable, even with very limited gate accuracies. 
M. Dobsicek, G. Johansson, V.S. Shumeiko and G. Wendin