The latest model of the Invisibility Cloak is here, and it has two major improvements on the last few models. It can actually wrap around the stuff it’s concealing — and you can’t see the cloak itself. Take a look!
This sounds less like science fiction than Greek myth. A cloak can be placed over an object, any object, and the object is made invisible. The cloak is made of gold—gold spun finer than any other substance, even light. This is what is making object disappear at UC Berkeley.
The gold in question is gold nanoantennas, and each antenna is about 80 nanometers, roughly one-ninth the size of the 730-nanometer length of the red light being manipulated. This is important because, unlike other cloaks, this cloak doesn’t show its edges. While other cloaks had great success in manipulating light that struck the main body of the cloak, it could not conceal itself. The “skip” where the real world ended and the cloak began was visible. In the video above, you can see what it looks like when the current invisibility cloak covers up a little bump.
Admittedly the bump is small. It’s only about 1,300 microns in area. But the important thing is it’s not possible, when the cloak is turned on, to see any of the contours of either the object or the cloak itself. Researcher Xiang Zhang told the Washington Post, “Each antenna is designed to react with the light and scatter it back. They actually delay the light, delay the reflection, in such a way that every point of your face would reflect light as if from a flat surface, like a mirror.”
This tiny cloak is a proof of concept that researchers hope, one day, to scale up enough to cover an actual face. That’s the other advantage of a cloak this thin—it’s not too bulky. Rather than draping it over something to conceal its curves, or using it to block a square area, people might use this cloak to conceal an odd bumpy shape, or even wrap it around a whole object. This is a cloak that’s fine enough to act as a cloak. Pretty neat!
Image: Berkeley Lab