A bathing cap that can watch individual neurons, allowing others to monitor the wearer’s mind. A sensor that can spot hidden nuclear submarines. A computer that can discover new drugs, revolutionize securities trading and design new materials. A global network of communication links whose security is underwritten by unbreakable physical laws.
Such—and more—is the promise of quantum technology.
All this potential arises from improvements in scientists’ ability to trap, poke and prod single atoms and wispy particles of light called photons. Today’s computer chips get cheaper and faster as their features get smaller, but quantum mechanics says that, at tiny-enough scales, particles sail through solids, short-circuiting a chip’s innards.
Quantum technologies come at the problem from the other direction. Rather than scale down devices, quantum technologies employ the unusual behaviors of single atoms and particles and scale them up. Like computerization before it, this unlocks a world of possibilities, with applications in nearly every existing industry—and the potential to spark entirely new ones.
Quantum mechanics, a theory of the behavior at the atomic level put together in the early 20th century, has a well-earned reputation for weirdness. That is because the world as humanity sees it is not, in fact, how the world works.
Quantum mechanics replaced wholesale the centuries-old notion of a clockwork, deterministic universe with a reality that deals in probabilities rather than certainties—one where the very act of measurement affects what is measured. Along with that upheaval came a few truly mind-bending implications, such as the fact that particles are fundamentally neither here nor there, but, until pinned down, both here and there at the same time: they are in a “superposition” of here-there-ness.
The theory also suggested that particles can be spookily linked: Do something to one and the change is felt instantaneously by the other, even across vast reaches of space. This “entanglement” confounded even the theory’s originators.
It is exactly these effects that show such promise now: The techniques that were refined in a bid to learn more about the quantum world now are being harnessed to put it to good use. Gizmos that exploit superposition and entanglement can vastly outperform existing ones and accomplish things once thought to be impossible.
Improving atomic clocks by incorporating entanglement, for example, makes them more accurate than those used today in satellite positioning. That could improve navigational precision by orders of magnitude, which would make self-driving cars safer and more reliable.
Because the strength of the local gravitational field affects the flow of time—according to general relativity, another immensely successful but counter-intuitive theory—such clocks also would be able to measure tiny variations in gravity. That could be used to spot underground pipes without having to dig up a road, or to track submarines far below the waves.
Other aspects of quantum theory permit messaging without worries about eavesdroppers. Signals encoded using either superposed or entangled particles cannot be intercepted, duplicated and passed on. China already has launched a satellite that can receive and reroute such signals.
The advantageous interplay between odd quantum effects reaches its zenith in quantum computers. Rather than the 0s and 1s of standard computing, a quantum computer’s bits are in superpositions of both, and each “qubit” is entangled with every other. Using algorithms that recast problems in quantum-amenable forms, such computers will be able to chomp their way through calculations that would take today’s best supercomputers millennia.
Even simple quantum computers should be able to tackle classes of problems that choke conventional machines, such as optimizing trading strategies or plucking promising drug candidates from scientific literature. Google said last week that such machines are only five years from commercial exploitability. Recently, IBM, which already runs a publicly accessible, rudimentary quantum computer, announced expansion plans. Big tech companies and startups alike are developing software to exploit these devices’ curious abilities. A new ecosystem of middlemen is emerging to match new hardware to industries that might benefit.
© 2017 Economist Newspaper Ltd., London (March 11).
All rights reserved. Reprinted with permission.