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Quantum Computer Simulates Hydrogen Molecule Just Right


quantum computer calculates molecular energy level.

Benjamin Lanyon

Almost three decades ago, Richard Feynman — known popularly as much for his bongo drumming and pranks as for his brilliant insights into physics — told an electrified audience at MIT how to build a computer so powerful that its simulations “will do exactly the same as nature.”

Not approximately, as digital computers tend to do when facing complex physical problems that must be addressed via mathematical shortcuts — such as forecasting orbits of many moons whose gravities constantly readjust their trajectories. Computer models of climate and other processes come close to nature but hardly imitate it. Feynman meant exactly, as in down to the last jot.

Now, finally, groups at Harvard and the University of Queensland in Brisbane, Australia, have designed and built a computer that hews closely to these specs. It is a quantum computer, as Feynman forecast. And it is the first quantum computer to simulate and calculate the behavior of a molecular, quantum system.

Much has been written about how such computers would be paragons of calculating power should anybody learn to build one that is much more than a toy. And this latest one is at the toy stage, too. But it is just the thing for solving some of the most vexing problems in science, the ones that Feynman had in mind when he said “nature” — those problems involving quantum mechanics itself, the system of physical laws governing the atomic scale. Inherent to quantum mechanics are seeming paradoxes that blur the distinctions between particles and waves, portray all events as matters of probability rather than deterministic destiny, and under which a given particle can exist in a state of ambiguity that makes it potentially two or more things, or in two or more places, at once.

From Wired
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