Invisibility cloaks like those seen in "Harry Potter" are one step closer to becoming a reality, following a breakthrough in the development of these futuristic devices. This bring developers one step closer to their quest for such a material.

Queen Mary University of London (QMUL) researchers created a new composite coating capable of enhancing specific properties of electromagnetic (em) radiation, such as light. Properly focused, this material is able to make curved objects appear flat to em radiation. Utilizing nano-size particles, investigators were able to make objects disappear, in an arrangement known as a graded index nanocomposite.

Hiding behind an invisibility cloak is still a dream for researchers, but this new development could lead to the creation of a new generation of antennae. These devices would be able to be mounted to a wide variety of surfaces, placed in a wider range of angles than is now possible.

"The design is based upon transformation optics, a concept behind the idea of the invisibility cloak. Previous research has shown this technique working at one frequency. However, we can demonstrate that it works at a greater range of frequencies making it more useful for other engineering applications, such as nano-antennas and the aerospace industry," Yang Hao from the School of Electronic Engineering and Computer Science at QMUL said.

The technology behind this newest invisibility cloak relies on a nanocomposite medium, composed of seven layers, each of which affects em radiation differently. This allows a covered object to remain hidden, even when viewed over a wide variety of wavelengths. By bending (refracting) or absorbing light, certain materials can prevent light from reflecting back to a viewer.

The object researchers made disappear was roughly the size of a tennis ball, which they coated with the multi-layer nanocomposite medium. This new technique utilizing a series of separate layers with varying properties may also be applied to other fields where waves are dominant, including sound.

"We demonstrated a practical possibility to use nanocomposites to control surface wave propagation through advanced additive manufacturing. Perhaps most importantly, the approach used can be applied to other physical phenomena that are described by wave equations, such as acoustics. For this reason, we believe that this work has a great industrial impact," said Luigi La Spada of QMUL.

Over the last few years, scientists have made some significant advances in the quest for a functioning invisibility cloak. In 2015, investigators from the Lawrence Berkeley National Laboratory announced the development of a microscopic invisibility shield. This technique could, theoretically, be scaled up in size.

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