60-Second Science

Quantum Physics Leads to Perfect Mirror

Researchers created a surface that gives photons no option within the rules of quantum mechanics but to bounce back off. Wayt Gibbs reports

When you brushed your teeth this morning, the image starting back at you from your bathroom mirror was imperfect. Now, I’m sure you’re a lovely person. It’s just that there is no such thing as a perfect mirror. Even the shiniest surface absorbs or transmits at least a tiny bit of the light that hits it.

Or so it was thought until recently, when Chia Wei Hsu and his colleagues at M.I.T. reported in Nature that they created a virtually perfect mirror. [Chia Wei Hsu et al., Observation of trapped light within the radiation continuum]

It’s made from the stuff of microchips: silicon, a layer of silicon dioxide, and on top a very thin film of silicon nitride, which is perforated by a grid of microscopic circular holes.

When light hits that sievelike surface at the just the right angle—about 35 degrees—the quantum wave functions that govern the light interfere in such a way that there is no viable path for the photons other than to bounce off. So that’s what they do.

This phenomenon should work for all kinds of waves—not just light, but also sound and even water waves. But the most obvious application is to make more efficient and powerful lasers. Dr. Evil, are you listening?

—Wayt Gibbs

[The above text is a transcript of this podcast.]

[Scientific American is part of Nature Publishing Group.]

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