Science Closer to Creating Invisibility Cloak

     (CN) — A functional invisibility cloak — once the stuff of science fiction — could be one step closer to becoming a reality, according to a study published Friday.
     Scientists at Queen Mary University of London have made an object disappear by using a composite material with nano-size particles that can enhance specific properties on the object’s surface.
     While this development is far from resulting in the invisibility cloak popularized in the “Harry Potter” series, it may lead to redesigning how antennas are tethered to their platform and antennas of different shapes and sizing being attached in awkward places using a variety of materials.
     The design is based on transformation optics — mathematical equations that can be used to direct light in a specific manner, similar to warping space.
     “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,” study co-author Yang Hao said.
     The researchers coated a curved surface with a nanocomposite medium, which has seven distinct layers where the electric property of each layer varies depending on the position. The effect “cloaks” the object, hiding it where the electromagnetic waves would otherwise have been scattered.
     Lead author Luigi La Spada also noted how the underlying design approach could be useful for other applications, including converting microwave to optics for the control of electromagnetic surface waves.
     “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,” La Spada said. “For this reason, we believe that this work has a great industrial impact.”
     Researchers from the United States said earlier this month that there’s a fundamental limit to how well cloaking devices can really work, based on the laws of physics. This means that the invisibility cloaks from “Harry Potter” are likely impossible to create.
     “It turns out that there are stringent constraints in coating an object with a passive material and making it look as if the object were not there, for an arbitrary incoming wave and observation point,” lead author Andrea Alu said at the time.

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