  A recurrence scheme is presented to decompose an $n$-qubit unitary gate to
the product of no more than $N(N-1)/2$ single qubit gates with small number of
controls, where $N = 2^n$. Detailed description of the recurrence steps and
formulas for the number of $k$-controlled single qubit gates in the
decomposition are given. Comparison of the result to a previous scheme is
presented, and future research directions are discussed.
