Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything

by Michio Kaku

Let’s now summarize all the bizarre features of the quantum theory that make quantum computers possible. 1. Superposition. Before you observe an object, it exists in many possible states. So an electron can be in two places at the same time. This vastly increases the power of a computer, since you have more states to calculate with. 2. Entanglement. When two particles are coherent and you separate them, they can still influence each other. This interaction takes place instantly. This allows atoms to communicate with each other, even when separated. This means that computer power grows exponentially as more and more qubits are added that can interact with each other, far faster than ordinary computers. 3. Sum over paths. When a particle moves between two points, it sums over all possible paths connecting these two points. The most likely path is the classical, nonquantum path, but all these other paths also contribute to the final quantum path of the particle. This means that even paths which are extremely unlikely may become real. Perhaps the paths of molecules that created life became real because of this effect, making life possible. 4. Tunneling. When faced with a large energy barrier, normally a particle fails to penetrate it. But in quantum mechanics, there is a small but finite probability that you can “tunnel” or penetrate through the barrier. This might be why the complex chemical reactions of life can proceed at room temperature, even without vast amounts of energy.