A method of performing a quantum Fourier transform in a quantum computing
circuit is disclosed. The method includes forming a quantum computing
circuit as a collection of two-qubit gates operating on a sequence of
input qubits. Auxiliary qubits are then interacted with the original
input qubits to place the auxiliary qubits in a state corresponding to an
output of a discrete Fourier transform of a classical state of the input
qubits. The original input qubits are then re-set to their ground state
by physically interacting the input qubits with the auxiliary qubits. The
auxiliary qubits are then transformed to a state representative of a
quantum Fourier transform of the sequence of input qubits.