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Magnetic chip breakthrough could boost computer energy efficiency

Mon 14 Mar 2016

Electrical waste

A revolutionary step in thermodynamics research holds the potential to dramatically reduce the power consumption of modern computers and mobile devices.

Engineers at the University of California, Berkeley, have proved that magnetic computer chips can operate with the lowest possible level of energy dissipation, achieving reductions of as much as one millionth the amount of energy used per operation by a conventional transistor.

The results, which were published last Friday in the peer-reviewed journal Science Advances, mark significant progress for powering today’s mobile technologies, which require hugely powerful processors on tiny, lightweight batteries. At a larger scale, the scientists note the increasing industrial demand for cloud data centres and the need to reduce their strain on national and global electrical networks.

“We wanted to know how small we could shrink the amount of energy needed for computing,” commented lead author Jeffrey Bokor, a professor of electrical engineering and computer sciences and faculty scientist at the Lawrence Berkeley National Laboratory. “The biggest challenge in designing computers and, in fact, all our electronics today is reducing their energy consumption.”

Chip manufacturing has only recently turned considerable efforts towards lowering energy usage, having previously prioritised loading up numbers of increasingly smaller and faster transistors. Bokor explained: “Making transistors go faster was requiring too much energy […] The chips were getting so hot they’d just melt.”

Screen Shot 2016-03-14 at 16.01.20Looking for alternatives to traditional transistors, which rely on the movement of electrons to switch between zeroes and ones, researchers are now trying to find models which take less energy to ensure clear and distinguishable signal between the two states, and therefore avoid creating excess heat.

Magnets emerged as a promising choice for this application as states can be easily identified by the direction of the magnet. It also takes equal amounts of energy for a magnetic piece to point left as it does to point right. “These are two equal energy states, so we don’t throw energy away creating a high and low energy,” said Bokor.

In this study, the Berkeley engineers developed the nanomagnets before testing them and confirming the Landauer limit. Named after IBM researcher Rolf Landauer, the rule suggests that in any computer, every bit operation must dissipate an absolute minimum amount of energy. A formula calculates this lowest limit, which amounts to around three zeptojoules – one hundredth the energy let off by a single atom when it gives up one photon of light.

The scientists used a new method to record the amount of energy dissipation when a nanomagnetic was flipped. A laser probe was used to monitor the direction that the magnet was pointing, and an external magnetic field was created to spin the magnet ‘up’ and ‘down’.

At room temperature, they found that the technique only took 15 millielectron volts of energy, or 3 zeptojoules – therefore demonstrating the Landauer limit.

While the team had previously suggested that the effect was possible in 2011 research, this is the first time that the limit has ever been achieved in trial conditions.


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