"Avalanching Nanoparticles" Deliver a Nanocrystal Component to Boost Future Optical Computing

Researchers from the Lawrence Berkeley National Laboratory, the Universidad Autónoma de Madrid, the Huazhong University of Science and Technology, Oregon State University, and Columbia University have discovered a luminescent form of nanocrystal that, they say, could lead to a dramatic boost to the efficiency of future computers.

"The extraordinary switching and memory capabilities of these nanocrystals may one day become integral to optical computing — a way to rapidly process and store information using light particles, which travel faster than anything in the universe," claims Artiom Skripka, assistant professor in the Oregon State University College of Science and first author on the paper. "Our findings have the potential to advance artificial intelligence and information technologies generally."

Constructed from "avalanching nanoparticles," which dramatically increase their light emission in response to only a minor increase in the intensity of the laser light being used to excite them, the breakthrough in the team's creation lies in the crystal's ability to be stable in two different states. "Normally, luminescent materials give off light when they are excited by a laser and remain dark when they are not," Skripka explains. "In contrast, we were surprised to find that our nanocrystals live parallel lives. Under certain conditions, they show a peculiar behavior: They can be either bright or dark under exactly the same laser excitation wavelength and power.

"If the crystals are dark to start with, we need a higher laser power to switch them on and observe emission, but once they emit, they remain emitting and we can observe their emission at lower laser powers than we needed to switch them on initially. It's like riding a bike – to get it going, you have to push the pedals hard, but once it is in motion, you need less effort to keep it going. And their luminescence can be turned on and off really abruptly, as if by pushing a button."

If these crystals, and their intrinsic optical bistability, can be integrated with photonic materials, that could mean a dramatic boost to both the performance and power efficiency of future optical computing systems — as well as devices used for medical imaging, environmental sensing, and telecommunications. "Our findings are an exciting development," Skripka admits, "but more research is necessary to address challenges such as scalability and integration with existing technologies before our discovery finds a home in practical applications."

The team's work has been published in the journal Nature Photonics under closed-access terms; an open-access preprint is available on Cornell's arXiv server.