Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything

by Michio Kaku

But the most crucial and outrageous statement is number four, which holds that only after a measurement is made will the wave finally “collapse” and yield the correct answer, giving the probability of finding the electron in that state. One cannot know which state the electron is in until a measurement is made. This is called the measurement problem. To refute the last statement, Einstein would say, “God does not play dice with the universe.” But according to legend, Niels Bohr fired back, “Stop telling God what to do.” It is precisely postulates 3 and 4 that make quantum computers possible. The electron is now described as the simultaneous sum over different quantum states, which gives quantum computers their calculational power. While classical computers only sum over just 0s and 1s, quantum computers sum over all quantum states Ψn(x) between 0 and 1, which vastly increases the number of states and therefore their range and power.