Paul Stevenson, a Northeastern physics professor, studies how nature utilizes electron spin in biomolecules to revolutionize computing.
Almost all modern technology relies on the ability of electrons to carry charge. This is essential for electricity, power transmission, electronic devices, battery storage and many other uses.
However, electrons possess another built-in property beyond charge — spin. Scientists have been trying to harness this property for years, says Paul Stevenson, an assistant professor of physics at Northeastern University, leading to the emergence of a new field called spintronics.
“People have tried to find ways to make new materials that can manipulate this spin property as well as the charge property,” he says.
Surprisingly, research over the last decade suggests that nature may have already mastered what scientists have been trying to engineer. Stevenson explains that biomolecules seem to naturally use this property of electrons.
“We’ve never really looked at them because why would we think nature is already able to do this thing that we’ve been trying to engineer for decades,” he says.
Stevenson recently received a prestigious Young Investigator Research Program grant from the Air Force Office of Scientific Research. This three-year grant will fund his research on quantum sensing techniques to detect spin-dependent electron transfer in proteins, helping to advance our understanding of these processes.
“Biological systems are naturally capable of performing many of the tasks required for spin-based electronics at room temperature and without external magnetic fields,” Stevenson says. “My research explores how we can use this toolkit provided by nature to explore fundamental physics and develop next-generation materials.”
The quantum physics term “spin” is somewhat misleading as electrons do not actually spin. However, they behave as if they have angular momentum, which determines their spin state — either spin-up or spin-down.
This property can be used in both classical and quantum computing, Stevenson says, similar to “1” and “0.”
Transistors, the building blocks of modern electronics, and central processing units (CPUs), the “brains” of computers, work by moving electrons to transmit charge. However, spin-based technology could eliminate the need for this physical movement.
“With spins, we can make [devices] talk to one another in a way that’s much more efficient and doesn’t necessarily need the actual electron physically to move,” Stevenson says. “Which means we could route information more efficiently if we could find things that were very good at generating these spin-pointing-up or spin-pointing-down states.”
His research seeks to determine whether biological systems can do this naturally and, if so, how they do it.
It appears, Stevenson says, that this capability stems from the intrinsic structure of biomolecules like proteins and DNA.
“This is something that all biomolecules seem to have and it is exciting in the sense that we could leverage all of nature’s machinery for making biomolecules,” he says. “It may be the most scalable manufacturing system, if you think about it. There are so many proteins being synthesized every second just in living things that we could sort of hijack that machinery to make new organic-based compounds.”
Studying biomolecules and taking advantage of what nature is already doing could save decades of new materials development efforts. Quantum physicists would be able to use the spin properties of electrons in biomolecules at room temperature and learn how to manufacture them. Although it is still a long journey, Stevenson says.
“The big application that we as a field would like to use these [materials] for is for new types of information processing that might be faster, or more robust, or more compact, or more energy efficient,” he says. “But that’s still probably a long way away because one of the big problems we don’t know is, fundamentally, why does this effect happen?”