Do cloaked objects shine brightly?

Invisibility cloaks might actually make the objects they aim to hide more visible, according to researchers in the US. While existing cloaking concepts might have the potential to render objects invisible to specific electromagnetic frequencies, a recent study has shown that, when integrating over the entire spectrum, the combined scattering of the cloak is always greater than the original uncloaked object. When exposed to short broadband pulses, these cloaks might therefore be turned instead into easier-to-see "beacons". The team proposes two solutions to this problem: a passive approach using thin shells of superconducting material; and an active solution based on metamaterials.