Heat flux is all around us—everywhere there’s a temperature difference. It’s intuitively easy to understand, at least at its most basic level: Heat flows from hot to cold and does so more readily through some materials than through others. But compared with the analogous flow of electric current, heat is much more difficult to control or put to good use. Better control of heat flux could help protect sensitive electronic components from temperature extremes, better harness solar thermal energy, or, more speculatively, create thermal analogues of electronic diodes and transistors.

Now Yuki Sato and his postdoc Supradeep Narayana, of the Rowland Institute at Harvard University, have used techniques from the field of metamaterials in order to manipulate heat flux.1 Inspired by work on devices that “cloak” regions from electromagnetic waves (see PHYSICS TODAY, February 2007, page 19), acoustic waves, static fields, and other signals, they set themselves the...

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