What do you mean with it? The quantum state of a two particle system? In that case I am pretty sure - even though I am not a physicist - that you are wrong. The quantum state of a two particle system can not be decomposed into two states, one state for each particle, in the general case. You can find the density matrix for each particle which will tell you how each corresponding particle will behave in isolation but you will lose information about the system by doing so in the general case.