Qubits, the strange devices at the heart of a quantum computer that can be set to 0, 1, or both at once, could hardly be more different from the mechanical clockwork used in the earliest computers. Today, most quantum computers rely on qubits made out of tiny circuits of superconducting metal, individual ions, photons, or other things. But now, physicists have made a working qubit from a tiny, moving machine, an advance that echoes back to the early 20th century when the first computers employed mechanical switches.