Realization of robust quantum computing is a tremendous task.On one hand,one must reduce errors as many as pos-sible using various means[1-3];on the other hand,one may make large error rates tolerable via fault-tolerant im-plementation.In achieving tolerant against noises,the cost to pay is the increased number of gates used.Therefore,an efficient implementation of fault-tolerant gates is crucial.As already evidenced,Clifford gates with a T gate can form a universal set of fault-tolerant gates.The optimal im-plementations for Toffoli and Fredkin gates were first pro-posed in ref.[4].In a recent study,Li et al.