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Graphene Enables Invisibility Cloak

Non-invasive sensors and low-scattering electronic components could benefit from graphene cloaks

1 min read
Graphene Enables Invisibility Cloak

Fans of the original "Star Trek" television show surely recall those dastardly Klingons employing a cloaking device that rendered their vessels invisible. Of course, that is science fiction, but in research coming out of the University of Texas at Austin, that capability sounds amusingly similar to a proposed use of graphene in providing an “active, dynamically tunable invisibility cloak.”

The research, which was originally published in the ACS journal Nano, builds on two fields of previous work. The first field is termed “plasmonic cloaking,” which uses metamaterial coatings, and the second is known as “mantle cloaking,” which achieves more or less the same effects as plasmonic cloaking but by using impedance.

"The graphene cloak idea stems from the mantle cloaking concept, which we have proposed at microwaves using frequency-selective surfaces, i.e., properly patterned conducting surfaces that can tailor their effective surface impedance at will," says Andrea Alù, at the University of Texas at Austin, in the Nanowerk article cited above.

Alù adds, "Due to the recent progress in understanding graphene's AC conductivity, we have realized that its unique features of ultrahigh mobility and largely tunable Fermi level may naturally provide the required reactive properties in a single atomic layer. The effective surface impedance of graphene can be tuned in real time, another great advantage of this graphene cloak, which makes dynamically tunable and switchable cloaking operation possible."

While invisible aircraft may leap to mind, the applications for this technology could be in the areas of noninvasive sensors and low-scattering electronic components.

"There is great interest in realizing low-scattering or impedance-matched electronic components, and we believe that the use of this graphene layer may realize this effect in an ultrathin geometry—much thinner than antireflection coatings or other available technology," says Alù.

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3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD

A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

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