  Exchange of quantum states between two interacting harmonic oscillator along
their evolution time is discussed. It is analyzed the conditions for such
exchange starting from a generic initial state and demonstrating that the
effect occurs exactly only for the particular states C0|0>+Cn|N>, which
includes the interesting qubits components |0>,|1>. It is also determined the
relation between the coupling constant and characteristic frequencies of the
oscillators to have the complete exchange.
