  In this paper we show that it is possible to adapt a qudit scheme for
creating a controlled-Toffoli created by Ralph et al. [Phys. Rev. A 75 011213]
to be applicable to qubits. While this scheme requires more gates than standard
schemes for creating large controlled gates, we show that with simple
adaptations it is directly equivalent to the standard scheme in the literature.
This scheme is the most gate-efficient way of creating large controlled
unitaries currently known, however it is expensive in terms of the number of
ancilla qubits used. We go on to show that using a combination of these
standard techniques presented by Barenco et al. [Phys. Rev. A 52 3457 (1995)]
we can create an n-qubit version of the Toffoli using less gates and the same
number of ancilla qubits as recent work using computer optimization. This would
be useful in any architecture of quantum computing where gates are cheap but
qubit initialization is expensive.
