F. Ghisi et Sv. Ulyanov, The information role of entanglement and interference operators in Shor quantum algorithm gate dynamics, J MOD OPT, 47(12), 2000, pp. 2079-2090
Shor algorithm dynamics of quantum computation states are analysed from the
classical and the quantum information theory points of view. The Shannon e
ntropy is interpreted as the degree of information accessibility through me
asurement, while the von Neumann entropy is employed to measure the quantum
information of entanglement. The intelligence of a state with respect to a
subset of qubits is defined. The intelligence of a state is maximal if the
gap between the Shannon and the von Neumann entropy for the chosen result
qubits is minimal. We prove that the quantum Fourier transform creates maxi
mally intelligent states with respect to the first n qubits for Shor's prob
lem, since it annihilates the gap between the classical and quantum entropi
es for the first n qubits of every output state.