Basically, any quantum system that can superimpose states of 0s and 1s and entangle them so that they can process this information can become a quantum computer. Electrons and ions that spin up or down could serve this purpose, or polarized photons that spin clockwise or counterclockwise. Since the quantum theory governs all matter and energy in the universe, there are potentially thousands of ways to build a quantum computer. In a lazy afternoon, a physicist may dream up scores of ways of representing the superposition of 0s and 1s to create an entirely new quantum computer.
