“The project exists in a simultaneous state of being both totally successful and not even started”. So blags the employee in a Dilbert cartoon about quantum computing. In the real world the same ambiguity exists. Computers that harness the counter-intuitive properties of subatomic particles are capable of astonishing processing speeds. But they have yet to prove their practical value.
Classical computers use bits, representing zeros and ones, to solve problems. Quantum computers use qubits. These can store multiple values at the same time, just as a cat can be both dead and alive in Schrödinger’s famous thought experiment. This hugely magnifies their computing power. That could open up new applications from pharmaceuticals to finance, worth up to $52bn in 2035, says McKinsey.
More than 50 start-ups have secured backing since 2012. But some researchers fear a funding boom will give way to bust, creating a “quantum winter” like that suffered by the artificial intelligence sector in the 1980s. The problem is that the high error rate of early prototypes is a barrier to commercial applications. Do not expect the same virtuous circle as conventional computers, where gradual improvements in technology generated increasing revenues that could be ploughed back into more research according to a US National Academies report.
Still, progress is being made. Last month, Google announced that its quantum computer had successfully simulated a simple chemical reaction. That might go some way to silence critics who thought its display, last Autumn, of quantum supremacy — performing calculations that had previously been impossible — lacked practical value.
Nor is industry being left to fund this technology alone. Governments, led by China, have pumped some $22bn into quantum technologies, says consultancy Qureca. Quantum computing, which could overturn existing encryption methods, has implications for national security. Though it may yet hit insuperable barriers, superpowers will not want to risk being left behind. The technology is unpredictable but its disruptive potential is huge.
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