Implementation of Quantum Fourier Transform and Simulation of Wave Functions by Fixed Interaction

We study a quantum computer with fixed and permanent interaction of diagonal type between qubits. It is controlled only by one-qubit quick transformations. It is shown how to implement Quantum Fourier Transform and to solve Shroedinger equations with linear and quadratic potentials by a quantum computer of such type. The method is adaptable to the wide range of interactions of diagonal form between qubits and to the case when different pairs of qubits interact variously.