Look out, Harry Potter: researchers have advanced the study of cloaking—rendering objects invisible by forcing light waves to act as if the objects weren't there.

In a paper published in this week's Science, a team from Duke University and Southeast University in Nanjing, China, reports a new and improved cloak that can conceal a bump—and anything hidden beneath—on a flat surface. Both the surface and the bump (visible at the far left in the photo) must be reflective, however. The new setup is upgraded to function for a relatively broad spectrum of light, whereas previous models had very narrow operational regimes.

This cloak, like its predecessors from the group of David Smith, an electrical and computer engineering professor at Duke, is built from metamaterials—novel composite structures designed to make light work in unusual ways.

Although the new cloak represents a step forward, even this "broadband" model is still a long way from rerouting visible light. The wavelengths of the microwave radiation regime in which the cloak works are tens of thousands of times longer than those of visible light.

Photo courtesy of Jack Mock