By asking this question i'm assuming that "memory" on a quantum computer works similarly compared to a regular computer in the sense that you can store information deterministically and when needed, retrieve it in the same way.
I'm also assuming that n qubit has 2^n "states" that can be set/read independently/concurrently
Let's suppose that in a 3 qubits quantum machine, at a certain point in time, after a bunch of other operations, I have set my 3 qBit to "111". In another words, those 3 qubits have a state that says "111" and other 7 states of irrelevant information.
At a later moment, given the superposition effect, how does one guarantee that reading those 3 men addrs will yield me my "111"s? In another words, how can I be sure that I'm reading the state that i set previously?