I have a little naive question. We know that quantum state is probabilistic and we can the count result from QASM simulator to know the distribution of various state a qubit can be in. Is there any way to show the state collapsed to deterministic one after measurement and show the probability is 1 at certain state after re-run the measurement?

Why I ask this, coz I feel a bit weird that the state does not collapsed as expected in Quantum Mechanics.


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Once you measure a qubit, it remains in the "result of measurement" with probability 100%. If you re-run the measurement you get the same result. The reason is that the measurement led to collapse of the qubit wave function and the qubit is now in classical state - either 0 or 1.

In theory the measured qubit remains in this state for indefinitely long. However, in practice it can be disturbed by a noise and flip to the other value. The same can happen in case of classical bits as well. This is reason why we use check sums and similar other techniques in classical computing.


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