Stephen Jeffrey

AS CALIFORNIA is to the United States, so British Columbia is to Canada. Both are about as far south-west as you can go on their respective mainlands. Both have high-tech aspirations. And, although the Fraser Valley does not yet have quite the cachet of Silicon Valley, it may be about to steal a march on its southern neighbour. For, on February 13th, D-Wave Systems, a firm based in Burnaby, near Vancouver, announced the existence of the world's first practical quantum computer.

On paper at least, quantum computers promise to reduce dramatically the time needed to solve a range of mathematical tasks known as NP-complete problems. One famous example is the travelling salesman problem—finding the shortest route between several cities. This is a puzzle that increases exponentially in complexity with the number of cities considered. The reason is that every possible permutation needs to be looked at in order to find the best.

Quantum computers provide a neat shortcut to solving such problems. They do so by encoding all possible permutations in the form of a small number of “qubits”. In a normal computer, bits of digital information are either 0 or 1. In a quantum computer these normal bits are replaced by a “superposition” (the qubit) of both 0 and 1 that is unique to the ambiguous world of quantum mechanics. Qubits have already been created in the laboratory using photons (the particles of which light is composed), ions and certain sorts of atomic nuclei. By a process known as entanglement, two qubits can encode four different values simultaneously (00, 01, 10 and 11). Four qubits can represent 16 values, and so on. That means huge calculations can be done using a manageable number of qubits. In principle, by putting a set of entangled qubits into a suitably tuned magnetic field, the optimal solution to a given NP-complete problem can be found in one shot.

The end of the beginning

D-Wave Systems chose two very practical problems to demonstrate its 16-qubit processor, which it has called Orion. One was a pattern-matching application for searching through a database of molecules—the sort of task that a drug company looking for the key to a particular molecular lock in a disease-causing protein might want to do routinely. The other was a scheduling application for assigning people to seats, subject to certain constraints. Airlines might be interested in that one.

The catch is that Orion is not exactly desktop friendly. It has to sit in a bath of liquid helium cooled to just a fraction of a degree above absolute zero (-273°C) in order to work. This is because it relies on a superconducting device called a Josephson junction to produce the qubits, in the form of specially tweaked electrons that are stable only at such low temperatures.

Impractical as this may sound, Geordie Rose, D-Wave's founder, is optimistic that it is the best way forward for quantum computing. Other techniques involve huge lumps of machinery, but Josephson junctions can be made using the sort of microfabrication technology employed for normal silicon chips. This means there is a realistic prospect of integrating quantum computers with conventional ones. Dr Rose favours this route, because he sees quantum computers as specialised accelerators for certain tasks, rather than stand-alone number crunchers.

Shrink-wrapped quantum computers labelled “Orion inside” are not, therefore, about to start shipping anytime soon. Quantum computing will be strictly mainframe for the foreseeable future. Nevertheless Dr Rose plans later this year to provide free, remote access to an Orion processor so that potential customers can try running their problems on it and evaluate its performance.

Whether D-Wave will do for southern British Columbia what Fairchild Semiconductor—the firm that made the first commercial integrated circuits—did for central California 50 years ago remains to be seen. The aspiration, however, was betrayed by D-Wave's choice of the Computer History Museum in Mountain View, near Fairchild's original home, to demonstrate Orion's potential. Come back in half a century to find out what happened.