The technology works by using a laser with a specific energy level to excite an electron, which is then “trapped” inside the structure. A larger version of this device could eventually store petabytes of information. (Image courtesy of Zhong's lab)
Scientists have developed a method for storing and reading data from individual atoms embedded in tiny crystals just a few millimeters across (where 1 mm is equivalent to 0.04 inches). If scaled up, this could eventually lead to ultra-dense storage systems capable of storing petabytes of information on a single disk — where 1 PB is equivalent to about 5,000 4K movies.
The encoding of data as ones and zeros has been around for as long as the history of computing, and the only difference is the medium used to store that data – from blinking vacuum tubes to tiny electronic transistors or even compact discs (CDs), where dimples on the surface represent ones and smooth areas represent zeros.
Now scientists are looking to store data even more densely, which is taking them into the subatomic world. In a new study published Feb. 14 in the journal Nanophotonics, the researchers used an electron captured by a defect in a crystal to represent a 1, while the absence of a captured electron indicates a 0.
The work was inspired by quantum methods, the scientists say. Specifically, they combined solid-state physics used in radiation dosimetry with a research group working on quantum storage, but this particular work relies on classical computing memory.
The technology is carried out by exciting an electron with a laser having a certain amount of energy. At this point, the reading device can detect the presence of light. The absence of light indicates the absence of a captured electron.
This only works if the crystals contain defects, such as oxygen vacancies or impurities. “These defects have very good characteristics,” the study’s lead author, Leonardo Franca, a postdoctoral fellow in physics at the University of Chicago, told Live Science. “One of these characteristics is the ability to hold a charge.”
With this in mind, the team used rare earth ions as dopants – impurities added to a material to change its properties – with the key being creating a way to excite an electron from a particular rare earth ion so that it would then become trapped. If you think about how CD works, this would be the equivalent of creating a pit.
“We have to provide enough energy to release the electron from the rare earth ion, and the defect — the nearby defect — will sense that,” Franca explained. “So you trap the electron with your own electric field. That's part of the writing process.”
Then comes the data-reading stage. “Basically, you need to use another light source to free the electron from the defect,” Franca said. “And that causes the charges to recombine, which in turn causes light to be emitted.”
Building the Data Warehouse of the Future
If the process worked exactly like that, the data would be erased each time it was read, but using less light would only “partially erase the information,” Franca said. So it would fade over time, just as the data on tapes fades over 10 to 30 years.
Although the team used the rare earth element praseodymium and a yttrium oxide crystal, the work could also be extended to other rare earth crystals with other undoped impurities. But rare earths have the advantage of providing known and defined wavelengths that allow us to excite electrons with standard lasers.
The researchers' original goal was to get down to individual atoms. While they haven't quite reached that goal yet, Franca believes the method the team pioneered is putting them on the right track.
According to France, the interest in further research is driven by the scalability of the technology, which could potentially lead to low-cost, high-density data storage formats in the future for a variety of applications.
Sourse: www.livescience.com
