Much has been made of the excessive power demands of AI, but solutions are sparse. This has led engineers to consider completely new paradigms in computing: optical, thermodynamic, reversible—the list goes on. Many of these approaches require a change in the materials used for computation, which would demand an overhaul in the CMOS fabrication techniques used today.
Over the past decade, Hector De Los Santos has been working on yet another new approach. The technique would require the same exact materials used in CMOS, preserving the costly equipment, yet still allow computations to be performed in a radically different way. Instead of the motion of individual electrons—current—computations can be done with the collective, wave-like propagations in a sea of electrons, known as plasmons.
De Los Santos first proposed the idea of computing with plasmons back in 2010. More recently, in 2024, De Los Santos and collaborators from University of South Carolina, Ohio State University, and the Georgia Institute of Technology created a device that demonstrated the main component of plasmon-based logic: the ability to control one plasmon with another. We caught up with De Los Santos to understand the details of this novel technological proposal.
How Plasmon Computing Works
IEEE Spectrum: How did you first come up with the idea for plasmon computing?
De Los Santos: I got the idea of plasmon computing around 2009, upon observing the direction in which the field of CMOS logic was going. In particular, they were following the downscaling paradigm in which, by reducing the size of transistors, you would cram more and more transistors in a certain area, and that would increase the performance. However, if you follow that paradigm to its conclusion, as the device sizes are reduced, quantum mechanical effects come into play, as well as leakage. When the devices are very small, a number of effects called short channel effects come into play, which manifest themselves as increased power dissipation.
So I began to think, “How can we solve this problem of improving the performance of logic devices while using the same fabrication techniques employed for CMOS—that is, while exploiting the current infrastructure?” I came across an old logic paradigm called fluidic logic, which uses fluids. For example, jets of air whose direction was impacted by other jets of air could implement logic functions. So I had the idea, why don’t we implement a paradigm analogous to that one, but instead of using air as a fluid, we use localized electron charge density waves—plasmons. Not electrons, but electron disturbances.
And now the timing is very appropriate because, as most people know, AI is very power intensive. People are coming against a brick wall on how to go about solving the power consumption issue, and the current technology is not going to solve that problem.
What is a plasmon, exactly?
De Los Santos: Plasmons are basically the disturbance of the electron density. If you have what is called an electron sea, you can imagine a pond of water. When you disturb the surface, you create waves. And these waves, the undulations on the surface of this water, propagate through the water. That is an almost perfect analogy to plasmons. In the case of plasmons, you have a sea of electrons. And instead of using a pebble or a piece of wood tapping on the surface of the water to create a wave that propagates, you tap this sea of electrons with an electromagnetic wave.
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