System Bits: Feb. 9

Hack-proof RFID chips; silicon-based photonics chips; silver atom switches light.

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Securing RFID chips
Researchers at MIT and Texas Instruments have developed a new type of radio frequency identification (RFID) chip that they say is virtually impossible to hack, and which could secure credit cards, key cards, and pallets of goods in warehouses.

The researchers reminded that if such chips were widely adopted, it could mean that an identity thief couldn’t steal your credit card number or key card information by sitting next to you at a café, and high-tech burglars couldn’t swipe expensive goods from a warehouse and replace them with dummy tags.

TI has already built several prototypes of the chip according to the research specifications. In experiments, they report the chips have behaved as expected.

Researchers have designed an RFID chip that prevents so-called side-channel attacks, which analyze patterns of memory access or fluctuations in power usage when a device is performing a cryptographic operation, in order to extract its cryptographic key. Pictured here is a standard RFID chip. (Source: MIT)

Researchers have designed an RFID chip that prevents so-called side-channel attacks, which analyze patterns of memory access or fluctuations in power usage when a device is performing a cryptographic operation, in order to extract its cryptographic key. Pictured here is a standard RFID chip. (Source: MIT)

According to Chiraag Juvekar, a graduate student in electrical engineering at MIT and first author on the new paper, the chip is designed to prevent side-channel attacks that analyze patterns of memory access or fluctuations in power usage when a device is performing a cryptographic operation, in order to extract its cryptographic key.

Enabling photonic circuits with silicon-based metamaterials
Purdue University researchers are developing transparent metamaterials that could make it possible to crete computer chips and interconnecting circuits that use light instead of electrons to process and transmit data, and representing a potential leap in performance.

While optical fibers are currently used to transmit large amounts of data over great distances, the technology cannot easily be miniaturized because the wavelength of light is too large to fit within the miniscule dimensions of microcircuits, the researchers reminded.

Transparent metamaterials, nanostructured artificial media with transparent building blocks, allow unprecedented control of light and may represent a solution, the team explained. They are making progress in developing metamaterials that shrink the wavelength of light, pointing toward a strategy to use light instead of electrons to process and transmit data in computer chips.

Silver atom switches light
In an effort to improve the efficiency of communications network components, ETH Zurich researchers have created what they believe is the world’s smallest integrated optical switch.

Network components must constantly be made more efficient, and these include modulators, which convert the information that is originally available in electrical form into optical signals. As such, modulators are nothing more than fast electrical switches that turn a laser signal on or off at the frequency of the incoming electrical signals. While they are installed in datacenters by the thousands, they have the disadvantage of being quite large. Measuring a few centimeters across, they take up a great deal of space when used in large numbers.

However, six months ago, a working group led by Jürg Leuthold, ETH Zurich Professor of Photonics and Communications already succeeded in proving that the technology could be made smaller and more energy-efficient. As part of that work, the researchers presented a micromodulator measuring just 10 micrometres across – or 10,000 times smaller than modulators in commercial use.

The switch is based on the voltage-induced displacement of one or more silver atoms in the narrow gap between a silver and a platinum plate. (Source: Alexandros Emboras / ETH Zurich)

The switch is based on the voltage-induced displacement of one or more silver atoms in the narrow gap between a silver and a platinum plate. (Source: Alexandros Emboras / ETH Zurich)

Leuthold and his colleagues have now taken this to the next level by developing the world’s smallest optical modulator, which they say is probably as small as it can get given that the component operates at the level of individual atoms. The footprint has therefore been further reduced by a factor of 1,000 including the switch together with the light guides. However, the switch itself is even smaller, with a size measured on the atomic scale.

The modulator works as such. As light entering from an optical fibre is guided to the entrance of the gap by the optical waveguide. Above the metallic surface, the light turns into a surface plasmon. A plasmon occurs when light transfers energy to electrons in the outermost atomic layer of the metal surface, causing the electrons to oscillate at the frequency of the incident light. These electron oscillations have a far smaller diameter than the ray of light itself. This allows them to enter the gap and pass through the bottleneck. On the other side of the gap, the electron oscillations can be converted back into optical signals, the team explained.

If a voltage is now applied to the silver pad, a single silver atom or, at most, a few silver atoms move towards the tip of the point and position themselves at the end of it. This creates a short circuit between the silver and platinum pads, so that electrical current flows between them. This closes the loophole for the plasmon; the switch flips and the state changes from “on” to “off” or vice versa. As soon as the voltage falls below a certain threshold again, a silver atom moves back. The gap opens, the plasmon flows, and the switch is “on” again. This process can be repeated millions of times. And as the plasmon has no other options than to pass through the bottleneck either completely or not at all, this produces a truly digital signal – a one or a zero — allowing for the creation of a digital switch, as with a transistor.