Quantum computer prototype. Researcher Neil Gershenfeld with his prototype of a quantum computer. The device (centre left) is a vial of water surrounded by magnets. A quantum computer uses molecules, in this case water molecules, to save and store information. The switches or bits in a conventional computer can only exist in 2 states, 0 or 1 (or on" or "off"). However, in a quantum computer the switches (or qubits) are molecules which can be both "on" and "off" at the same time. This makes a quantum computer far more powerful than conventional computers. Gershenfeld is a researcher at the Massachusetts Institute of Technology (MIT), USA."