i am not getting how a quantum computer will work. what i know is that for input they will use a superposition having states with different amplitudes.Then hermitian or unitary operators will interct with the input superposition to give the output superposition. Then error coding will give an accurate output. physically, any interaction will destroy the superposition instantaneously. so how will the physical analog of hermitian or unitary operators will be formed. Can superposition be created ?? where is entanglement supposed to be used here?