  To build a general-purpose quantum computer, it is crucial for the quantum
devices to implement classical boolean logic. A straightforward realization of
quantum boolean logic is to use auxiliary qubits as intermediate storage. This
inefficient implementation causes a large number of auxiliary qubits to be
used. In this paper, we have derived a systematic way of realizing any general
m-to-n bit combinational boolean logic using elementary quantum gates. Our
approach transforms the m-to-n bit classical mapping into a t-bit unitary
quantum operation with minimum number of auxiliary qubits, then a variation of
Toffoli gate is used as the basic building block to construct the unitary
operation. Finally, each of these building blocks can be decomposed into
one-bit rotation and two-bit control-U gates. The efficiency of the network is
taken into consideration by formulating it as a constrained set partitioning
problem.
