Magnetic Microprocessors: The Pure Logic of Magnetism…

In our overtly connected lives the CPU – Central Processing Unit or Microprocessor – is the engine that drives this connectivity. In the not too distant future a new generation processor is lifting it’s head just above the horizon. Based on tiny nano-magnets instead of tiny transistors, the Nano-Magnet Microprocessor is on the rise.

Relying on magnetic fields rather than electric current – flow of electrons – the Magnetic-Nano Processor could be up to 1,000,000 times more power efficient than current processors. Working at the very limits of possible efficiency might allow laptops to run for a thousand hours between charges, will an iPhone 10 be good for two days on a single charge, it is possible, the Nano-Magnetic Processor revolution is almost on us.

“Today, computers run on electricity; by moving electrons around a circuit, you can process information,” said Brian Lambson, a UC Berkeley graduate student in the Department of Electrical Engineering and Computer Sciences. “A magnetic computer, on the other hand, doesn’t involve any moving electrons. You store and process information using magnets, and if you make these magnets really small, you can basically pack them very close together so that they interact with one another. This is how we are able to do computations, have memory and conduct all the functions of a computer.”

UC Berkeley professor Jeffrey Bokor and graduate students Brian Lambson, David Carlton have been working to develop a functional magnetic processor that uses magnets as both memory storage and logic processing. The findings of their initial analysis have been published in the journal APS – American Physical Society – Physical Review Letters.

Through many calculations and simulations Lambsons has estimated that a simple memory operation such as clearing a memory bit can be done with the absolute minimum of power, in this case 18 millielectron volts – it takes 624 electronvolts to run a 100w light bulb for 1 second -, the minimum estimated by the Landauer limit principle. The Landauer limit is a principle first postulated by Randolf Landeuer and relates to the fact that every computer operation carried out by the logic in a microprocessor uses a tiny bit of energy, energy that you will never recover. In a transistor based microprocessor power is lost due to electrical resistance, one of the many difficulties in controlling electrons. The resistance causes power to be converted to heat, loosing efficiency and limiting the speed at which the chip can run, the speed is set by the maximum heat dissipation that can be done in the chips space / size. IBM has recently demonstrated a processor made with Graphene that limited the power loss and heat generated allowing the chip to run at 100Ghz, while most laptops and desktops today run at 2-3Ghz.

While the use of magnets as memory is a natural fit by simply using the direction of the poles to represent a 1 or 0, using magnets to perform logic operations such as simple math is very clever indeed, Nano-magnetic logic. The designers are taking advantage of strange behaviour observed in very small magnets, nano-magnets. The nano-magnets being used are 100 microns by 200 microns in size, when they are arranged closeley enough together the magnetic fields can interact. Altering the magnetic field of one will have a cascade effect on surrounding magnets, allowing simple additions. The next generation ciruit will use directly controlled magnetism to switch the field direction of surrounding magnets, a much more complex circuit than the current external electro-magnets used.

Nano-Magnet Processors also open the possibilities of powering processors with motion, heat, or RF harvesting power sources which have traditionally been seen as to low power to be of much use. Current computer processors use far too much power – upto 125 watts – to be able to be powered by any low power supply system. A magnetic processor on the other hand could be powered by any crazy method of converting motion or energy into power. At the moment most of these low power systems are used for RFID and near field payment systems on all new credit cards.

By using materials such as exotic semiconductors – Graphene, SiGe – and cooling it close to absolute zero a superconducting electro-magnetic processor could be possible and be theoretically capable of well over 100Ghz while still using 1,000,000 times less power than a modern CPU. “We are working now with collaborators to figure out a way to put that energy in without using a magnetic field, which is very hard to do efficiently,” Bokor said. “A multiferroic material, for example, may be able to control magnetism directly with a voltage rather than an external magnetic field.” Even though this early work is a simple design the future will become a lot more complex. Circuits that use hybrid semiconductor and magnetic elements together, the introduction of superconducting circuits with magnetic circuits are all possibilities being explored.

There are of course other competing technologies waiting in the wings to take over when transistors hit their limits. Optical computing is being developed by many R&D facilities and touted as a possible next generation technology. Optical chips are very similar to todays CPU’s except that they use the flow of photon’s instead of electrons to do the processing work. The speed of light is much faster than electrons so photonic computing operates at a whole other level of speed, 100Ghz and above are easily possible using photonics.

Nano-magnetic circuits are very compatible with the current transistor designs, this should allow them to be gradually integrated into current processor technology, something that photonic computing is struggling to do. Creating a hybrid design that uses the best of both worlds, high-speed and low power computing. Nano-Magnetic computing, more than just a catchy title this is a whole new kind of technology that will influence computing and gadgets of the near future.

More information at APS Pysics Review, ScienceDaily

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