Scientists, including an Oregon State University chemistry researcher, have taken a crucial step
toward next-generation optical computing and memory with the discovery of luminescent
nanocrystals that can be quickly toggled from light to dark and back again.
“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,” said Artiom Skripka, assistant
professor in the OSU College of Science. “Our findings have the potential to advance artificial
intelligence and information technologies generally.”
Published in Nature Photonics, the study by Skripka and collaborators at Lawrence Berkeley
National Laboratory, Columbia University, and the Autonomous University of Madrid involves a
type of material known as avalanching nanoparticles.
Nanomaterials are tiny bits of matter measuring between one-billionth and
one-hundred-billionths of a meter, and avalanching nanoparticles feature extreme non-linearity
in their light-emission properties—they emit light whose intensity can increase massively with a
small increase in the intensity of the laser that’s exciting them.
The researchers studied nanocrystals composed of potassium, chlorine, and lead and doped
with neodymium. By themselves, the potassium lead chloride nanocrystals do not interact with
light; however, as hosts, they enable their neodymium guest ions to handle light signals more
efficiently, making them useful for optoelectronics, laser technology, and other optical
applications.
“Normally, luminescent materials give off light when they are excited by a laser and remain dark
when they are not,” Skripka said. “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.”
That behavior is referred to as intrinsic optical bistability.
“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,” Skripka said. “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.”
The low-power switching capabilities of the nanocrystals align with the global effort to reduce the
amount of energy consumed by the growing presence of artificial intelligence, data centers, and
electronic devices. And not only do AI applications require substantial computational power,
they are often constrained by limitations associated with existing hardware, a situation this new
research could also address.
“Integrating photonic materials with intrinsic optical bistability could mean faster and more
efficient data processors, enhancing machine learning algorithms and data analysis,” Skripka
said. “It could also mean more-efficient light-based devices of the type used in fields like
telecommunications, medical imaging, environmental sensing, and interconnects for optical and
quantum computers.”
Broader Implications for Technology and Society
This groundbreaking discovery not only sets the stage for enhanced computational speed but
also has broader implications across multiple industries. The ability to switch light signals on
and off at low power could revolutionize telecommunications by enabling faster data transfer
rates with less energy consumption. For instance, the development of energy-efficient optical
transceivers and photonic switches could dramatically improve the performance of fiber-optic
networks, making internet connections faster and more reliable.
In the medical field, the use of such nanocrystals in imaging technologies could provide sharper,
more detailed images at reduced power levels, minimizing patient exposure to high-intensity
light or radiation. Similarly, in environmental monitoring, highly sensitive light-based sensors
could detect trace amounts of pollutants or greenhouse gases with unprecedented accuracy,
aiding in efforts to combat climate change.
Moreover, the bistable nature of these nanocrystals could play a pivotal role in quantum
computing, where precise control over light and matter interactions is essential. By harnessing
the unique properties of avalanching nanoparticles, researchers could develop quantum bits
(qubits) with enhanced stability and efficiency, further accelerating progress in this emerging
field.
A Path to Greener Computing
The environmental benefits of this innovation cannot be overstated. As global data usage
continues to soar, data centers—which power everything from streaming services to cloud
computing—are consuming vast amounts of electricity, contributing significantly to carbon
emissions. Transitioning to optical computing technologies that utilize bistable nanocrystals
could drastically cut energy consumption in these facilities, aligning with global sustainability
goals.
The potential for greener computing extends to personal devices as well. Smartphones, laptops,
and other consumer electronics could integrate these nanocrystals to deliver higher
performance while extending battery life. Such advancements could reduce electronic waste
and lower the environmental footprint of the tech industry.
Challenges and Future Research Directions
While the discovery of luminescent nanocrystals marks a significant milestone, several
challenges remain before their practical implementation can be realized. Scalability is a primary
concern; producing these nanocrystals in large quantities without compromising their unique
properties will require innovative manufacturing techniques. Additionally, researchers must
address issues related to integrating these materials with existing semiconductor technologies
to ensure seamless adoption.
Further studies are also needed to explore the long-term stability and durability of the
nanocrystals under various operating conditions. Ensuring that they can withstand the rigors of
real-world applications—from the intense heat of data centers to the harsh environments of
outer space—will be critical for their success.
“Our findings are an exciting development, 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,” Skripka said.
Support and Collaboration
The U.S. Department of Energy, the National Science Foundation, and the Defense Advanced
Research Projects Agency supported the research, which was led by Bruce Cohen and Emory
Chan of Lawrence Berkeley, P. James Schuck of Columbia University, and Daniel Jaque of the
Autonomous University of Madrid. This collaboration underscores the importance of
interdisciplinary efforts in driving scientific innovation and addressing global challenges.
As researchers continue to explore the potential of luminescent nanocrystals, their work
promises to redefine the boundaries of what is possible in computing, communication, and
beyond. By harnessing the power of light, they are paving the way for a brighter, more
energy-efficient future.