Yet another type of memory. Absolutely futuristic and not a viable current competitor IMO. Long term there will always be ingenious developments. to improve on existing technologies.
https://www.eenewseurope.com/en/researchers-store-terabytes-of-data-in-crystal-memory/Researchers store terabytes of data in crystal memoryTechnology News | February 17, 2025
By Jean-Pierre Joosting
University of Chicago Pritzker School of Molecular Engineering (UChicago PME) researchers have explored a technique to make ones and zeroes out of crystal defects, each the size of an individual atom for classical computer memory applications.The result of an interdisciplinary approach, the innovation leverages quantum techniques to turn research on radiation dosimeters — devices that store how much radiation hospital workers absorb from X-ray machines — into groundbreaking microelectronic memory storage.
“Each memory cell is a single missing atom — a single defect,” said UChicago PME Assistant Professor. Tian Zhong. “Now you can pack terabytes of bits within a small cube of material that’s only a millimeter in size.”
“We found a way to integrate solid-state physics applied to radiation dosimetry with a research group that works strongly in quantum, although our work is not exactly quantum,” said first author Leonardo França, a postdoctoral researcher in Zhong’s lab. “There is a demand for people who are researching quantum systems, but at the same time, there is a demand for improving the storage capacity of classical non-volatile memories. And it’s on this interface between quantum and optical data storage where our work is grounded.”
It all started during França’s PhD research at the University of São Paulo in Brazil, where he was studying radiation dosimeters.
“In the hospitals and particle accelerators, for instance, it’s needed to monitor how much of a radiation dose people are exposed to,” said França. “Some materials can absorb radiation and store that information for a certain amount of time.”
Through optical techniques, shining a light, França could manipulate and “read” that information.
“When the crystal absorbs sufficient energy, it releases electrons and holes. And these charges are captured by the defects,” França said. “We can read that information. You can release the electrons, and we can read the information by optical means.”
Seeing the potential for memory storage, França brought this non-quantum work into Zhong’s quantum laboratory to leverage quantum techniques to build classical memories.
The memory storage technique uses “rare earth” ions (lanthanides) — specifically a rare-earth element called Praseodymium and a Yttrium oxide crystal. However, the process could be used with various materials, taking advantage of rare earths’ powerful, flexible optical properties.
“It’s well known that rare earths present specific electronic transitions that allow you to choose specific laser excitation wavelengths for optical control, from UV up to near-infrared regimes,” França said.
Unlike dosimeters, which are activated by X-rays or gamma rays, the crystal memory storage device is activated using a simple ultraviolet laser. The laser stimulates the lanthanides, which in turn release electrons. The electrons are trapped by some of the oxide crystal’s defects — for instance, the individual gaps in the structure where a single oxygen atom should be but isn’t.
“It’s impossible to find crystals — in nature or artificial crystals — that don’t have defects,” França said. “So what we are doing is taking advantage of these defects.”
While these crystal defects are often used in quantum research, entangled to create “qubits” in gems from stretched diamond to spinel, the UChicago PME team found another use. They were able to guide when defects were charged and which weren’t. By designating a charged gap as “one” and an uncharged gap as “zero,” they turned the crystal into a powerful memory storage device.
“Within that millimeter cube, we demonstrated there are about at least a billion of these memories — classical memories, traditional memories — based on atoms,” Zhong said.
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