A team of Berkeley researchers has successfully crafted an ultra-thin invisibility “skin” cloak that can match any background.
Most of J.K. Rowling’s fantastical ideas in the Harry Potter series are frustratingly beyond the reach of us Muggles, but thanks to a team of Berkeley researchers, the elusive invisibility cloak has become a possibility. The scientists crafted an ultra-thin invisibility cloak that can conceal an object from detection in any visible light. Right now, the “skin” cloak is only microscopic, but the researchers are confident they’ll be able to scale it up to a useful size.
The cloak, just about 80 nanometers in width, is made up of metamaterials — materials that are artificially engineered with properties that aren’t found in nature. It works by scattering any type of light (visible, infrared, X-ray, etc.), thus preventing it from reflecting back to the observer’s eyes. Instead, the invisibility cloak is engineered to bend the light waves so that the observer sees whatever the background may be, rendering the object undetectable.
"This is the first time a 3D object of arbitrary shape has been cloaked from visible light," said Xiang Zhang, director of Berkeley Lab's Materials Sciences Division. "Our ultra-thin cloak now looks like a coat. It is easy to design and implement, and is potentially scalable for hiding macroscopic objects.”
In the experiment, the researchers wrapped the cloak around a microscopic object about the size of a few biological cells, shaped with multiple bumps and dents. According to the researchers, the cloak is thin and light, enabling it to be wrapped around virtually anything and still function properly.
However, there is one drawback — since the tuning has to be matched to the background for the cloak to work, if a hypothetical wizard was wearing the cloak, he’d have to stay still for it to render him invisible. Zhang says that there’s still much more work that needs to be done, and it could take up to 10 years to make the technology practical to use.
But the researchers have some exciting applications in mind. Xingjie Ni, a professor of electrical engineering and the study’s lead author, says the cloak could eventually be used for military purposes like making vehicles, aircrafts, and even individual soldiers “invisible.” Interestingly, he mentioned some more unconventional uses like cloaking pimples and wrinkles on the face, or fashioning a cloak “to hide one’s belly.” Even invisibility cloaks at the microscopic level could prove useful for security encryption purposes.
This isn’t the first time that researchers have attempted to craft an invisibility cloak. Previous cloaks were too bulky and harder to “scale up” to become useful for larger applications, but the researchers said they overcame the drawbacks that stunted the prior attempts. As leading pioneers in this burgeoning department of materials sciences, the team at Berkeley has raised the bar to exciting new heights.
No matter how the applications of the invisibility cloak evolve, the researchers’ ability to manipulate the interactions between light and metamaterials to render objects invisible is incredibly exciting. An invisibility cloak was once an idea that seemed like it could only exist in a magical realm, but thanks to science, it could be a reality on our very own planet in the years to come.