A significant advance in quantum plasmonics, fresh insights into the fundamental traits of surface plasmons have been discovered, challenging the existing understanding.
While prior research in the field has predominantly focused on the collective behaviours of plasmonic systems, researchers at Louisiana State University’s Quantum Photonics Group took a different approach.
By viewing plasmonic waves as a puzzle, they were able to isolate multiparticle subsystems, or break down the puzzle into pieces. This allowed the team to see how different pieces work together and revealed a different picture, or in this case, new behaviours for surface plasmons.
Inverse patterns, sharper patterns, and opposite interference
Plasmons are waves that move along the surface of metals when light is coupled to charge oscillations. Much like tossing pebbles into water generates ripples, plasmons are “ripples” travelling along metal surfaces. These minute waves operate on a nanometre scale, rendering them crucial in fields such as nanotechnology and optics.
“What we found is that if we look at the quantum subsystems of plasmonic waves, we can see inverse patterns, sharper patterns, and opposite interference, which is completely opposite to the classical behaviour,” explained Riley Dawkins, a graduate student and co-first author of a study published in Nature Physics.
Quantum subsystems can exhibit non-classical behaviours
Using light aimed at a gold nanostructure and observing the behaviour of scattered light, the LSU quantum group observed that surface plasmons can exhibit characteristics of both bosons and fermions, which are fundamental particles in quantum physics. This means that quantum subsystems can exhibit non-classical behaviours, such as moving in different directions, depending on specific conditions.
“Imagine you are riding a bike. You would believe that most of your atoms are moving in the same direction as the bike. And that is true for most of them. But in fact, there are some atoms moving in the opposite direction,” explained Associate Professor Omar Magaña-Loaiza.
“One of the consequences of these results is that by understanding these very fundamental properties of plasmonic waves, and most importantly, this new behaviour, one can develop more sensitive and robust quantum technologies.”
In 2007, the use of plasmonic waves for anthrax detection sparked research into employing quantum principles for improved sensor technology. Presently, researchers are striving to integrate these principles into plasmonic systems to create sensors with heightened sensitivity and precision.
This advancement holds significant promise across diverse fields, including medical diagnostics, drug development simulations, environmental monitoring, and quantum information science.
