While some scientists are working on an invisibility cloak to hide things, Cornell postdoctoral researcher Moti Fridman and his colleagues have been working on a "temporal cloak," to hide events in time.
A physical object or even another beam of light in the laser beam’s path could create a change in the laser light that the detector would register. But with some clever optics, Fridman and his colleagues were able to open up a brief time gap in the beam and then close it back up as if the beam had gone undisturbed, and such that the detector did not register the interruption. The gap allows anything that would have otherwise affected the beam to instead slip right through [see animation below], leaving no trace for the detector to pick up.
The events that can slip through the cloak have to be very fast: the gap is only 50 trillionths of a second. The video at the link explains the process much more clearly. Link -via Monkeyfilter