Comment on 'Universal quantum circuit for two-qubit transformations with three controlled-NOT gates' and 'Recognizing small-circuit structure in two-qubit operators'

摘要

Recent papers in Physical Review A have considered small quantum circuit decompositions in terms of a minimal number of controlled-NOT (CNOT) gates. Specifically, we point out errors in the papers by Vidal and Dawson [Phys. Rev. A 69, 010301 (R) (2004)] and by Shende et al. [Phys. Rev. A 70, 012310 (2004)].