Researchers from Arizona University have found a new way to translate the elusive magnetic spin of electrons into easily measurable electric signals.
They believe their findings will be a key step in the development of computing based on spintronics, which doesn't rely on electron charge to digitise information. "Spintronics has the potential to overcome several shortcomings of conventional, charge based computing," said Philippe Jacquod, an associate professor at the University's College of Optical Sciences. "Microprocessors store information only as long as they are powered up, which is the reason computers take time to boot up and lose any data in their working memory if there is a loss of power. "In addition, charge based microprocessors are leaky, meaning they have to run an electric current all the time just to keep the data in their working memory at their right value. That's one reason why laptops get hot while they're working. Spintronics avoids this because it treats the electrons as tiny magnets that retain the information they store even when the device is powered down. That might save a lot of energy." In their recent research paper, published in Physical Review Letters, Jacquod and his postdoctoral assistant, Peter Stano, proposed a protocol that made use of existing technology and required only small magnetic fields to measure the spin of electrons. "We took advantage of a nanoscale structure known as a quantum point contact, which one can think of as the ultimate bottleneck for electrons," Jacquod explained. "As the electrons were flowing through the circuit, their motion through that bottleneck was constrained by quantum mechanics. Placing a small magnetic field around that constriction allowed us to measure the spin of the electrons." Jacquod was then able to read out the spin of the electrons based on how the current through the bottleneck changed as he varied the magnetic field around it. "Looking at how the current changed told us about the spin of the electrons. Our experience tells us that our protocol has a very good chance to work in practice because we have done similar calculations of other phenomena. That gives us the confidence in the reliability of these results." In addition to being able to detect and manipulate the magnetic spin of the electrons, Jacquod anticipates that the work will offer a step forward in terms of quantifying it. He and Stano are now looking to extend their research to deal with electrons one by one, a feat that has yet to be accomplished.