An AI-designed invisibility cloak should be able to hide objects from infrared light or microwaves and be made from readily available materials. The device, which is currently being built, could eventually be used to hide antennas and similar communication devices from detectors.
Two decades ago, the invention of metamaterials took invisibility cloaks from fiction to laboratories. We see objects because light bounces off them and into our eyes. Metamaterial cloaks hide objects by manipulating that light to make it appear to be coming from empty space. However, most only work for one type of light and for very tiny objects.
at Xiamen University in China and his colleagues set out to try an alternative approach that skips metamaterials altogether, using an AI to design invisibility cloaks from other simpler materials.
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The researchers decided to try to design an invisibility cloak for a small cylindrical fibre. From past experiments, they knew that layers of a ceramic material and a boron and nitrogen compound should be able to do the job but the best composition was unknown.
To finesse these designs, the researchers used an AI inspired by biological evolution 鈥� after they input a set of cloak designs, it tweaked or 鈥渕utated鈥� them, then selected those that were best at stopping light from bouncing off them. The 鈥渕utations鈥� involved changing properties like the thickness of the layers of the cloak to alter which wavelengths of light it worked against.
The AI then repeated the process many times. Eventually, it output a single design that the researchers then simulated on a computer. Specifically, they simulated one cylinder with a 25-micron diameter that they wanted to hide from microwaves and another that was 6 centimetres wide that they wanted to obscure from infrared light. In either case, the simulations showed that the cloak would make the cylinder invisible to a device that detects these wavelengths.
Chen says that cloaks made by the AI method could be used to hide antennas and communication devices. The researchers are currently building physical prototypes.
at the City University of New York says that the method may not work for large objects because the AI has so far only optimised cloaks for objects comparable to the size of the wavelength of light they are being hidden from. Objects that we see with our eyes, for instance, are millions of times larger than the wavelengths of visible light. Chen says that for large objects the team would have to use more complex algorithms.
Physical Review E
