Measurement rules summary

Born rule (computational basis)

If $|\psi\rangle = \alpha|0\rangle + \beta|1\rangle$, then measuring in the computational basis yields:

• $P(0)=|\alpha|^2$
• $P(1)=|\beta|^2$

Post-measurement state (intuition)

After observing an outcome, the state updates toward the corresponding basis state (or eigenspace).