topological quantum computing

technologyreview |  In 2012, physicists in the Netherlands announced a discovery in particle physics that started chatter about a Nobel Prize. Inside a tiny rod of semiconductor crystal chilled cooler than outer space, they had caught the first glimpse of a strange particle called the Majorana fermion, finally confirming a prediction made in 1937. It was an advance seemingly unrelated to the challenges of selling office productivity software or competing with Amazon in cloud computing, but Craig Mundie, then heading Microsoft’s technology and research strategy, was delighted. The abstruse discovery—partly underwritten by Microsoft—was crucial to a project at the company aimed at making it possible to build immensely powerful computers that crunch data using quantum physics. “It was a pivotal moment,” says Mundie. “This research was guiding us toward a way of realizing one of these systems.”

Microsoft is now almost a decade into that project and has just begun to talk publicly about it. If it succeeds, the world could change dramatically. Since the physicist Richard Feynman first suggested the idea of a quantum computer in 1982, theorists have proved that such a machine could solve problems that would take the fastest conventional computers hundreds of millions of years or longer. Quantum computers might, for example, give researchers better tools to design novel medicines or super-efficient solar cells. They could revolutionize artificial intelligence.

Progress toward that computational nirvana has been slow because no one has been able to make a reliable enough version of the basic building block of a quantum computer: a quantum bit, or qubit, which uses quantum effects to encode data. Academic and government researchers and corporate labs at IBM and Hewlett-Packard have all built them. Small numbers have been wired together, and the resulting devices are improving. But no one can control the physics well enough for these qubits to serve as the basis of a practical general-purpose computer.

Microsoft has yet to even build a qubit. But in the kind of paradox that can be expected in the realm of quantum physics, it may also be closer than anyone else to making quantum computers practical. The company is developing a new kind of qubit, known as a topological qubit, based largely on that 2012 discovery in the Netherlands. There’s good reason to believe this design will be immune from the flakiness plaguing existing qubits. It will be better suited to mass production, too. “What we’re doing is analogous to setting out to make the first transistor,” says Peter Lee, Microsoft’s head of research. His company is also working on how the circuits of a computer made with topological qubits might be designed and controlled. And Microsoft researchers working on algorithms for quantum computers have shown that a machine made up of only hundreds of qubits could run chemistry simulations beyond the capacity of any existing supercomputer.

In the next year or so, physics labs supported by Microsoft will begin testing crucial pieces of its qubit design, following a blueprint developed by an outdoorsy math genius. If those tests work out, a corporation widely thought to be stuck in computing’s past may unlock its future.

Stranger still: a physicist at the fabled but faded Bell Labs might get there first.