http://spectrum.ieee.org/computing/hardware/loser-dwave-does...
"D-Wave's system uses a chip with little loops of niobium metal containing Josephson junctions—two superconductors separated by an insulator. When the chip is cooled to very low temperatures, tiny electrical currents flowing around the loops exhibit quantum properties, and you can use the direction to represent the states of a qubit: Counterclockwise represents 0, clockwise represents 1, and current flowing both ways represents a superposition of 0 and 1.
D-Wave's superconducting qubits are not new, and other groups use similar devices. But whereas most groups are trying to build the quantum logic gates from which all computing operations can be derived—an approach known as the gate model—D-Wave has adopted a different approach, called adiabatic quantum computation. Here's the gist: You initialize a collection of qubits to their lowest energy state. You then ever so gently (or adiabatically) turn on interactions between the qubits, thus encoding a quantum algorithm. In the end, the qubits drift to a new lowest-energy state. You then read out the qubits to get the results."