World First: IBM Researchers Store Data On a Single Atom

IBM researchers have read and written data to a magnet consisting of just one atom for the first time ever. The company’s research results, published in Nature, prove that “the experiment truly creates a lasting, stored magnetic state in a single atom that can be detected indirectly,” TechCrunch reports.

“Magnetic bits lie at the heart of hard-disk drives, tape and next-generation magnetic memory,” said Christopher Lutz, lead nanoscience researcher at IBM Research Almaden in San Jose, California.

“We conducted this research to understand what happens when you shrink technology down to the most fundamental extreme — the atomic scale.”

How Big Is a Bit Today?

A bit is the smallest unit of digital information, a single 1 or 0. On a hard drive, each bit is stored as a tiny magnetized area of the disk, and the direction of its magnetism tells the computer whether it’s a 1 or a 0.

Those areas are already very small, but they’re still made of a lot of atoms. According to PCWorld’s coverage of the announcement, current hard drives use about 100,000 atoms to store a single bit. Shrinking that to one atom is about as far as the idea can go.

How the Experiment Worked

The team, which included researchers from IBM and the Swiss university EPFL, used atoms of the rare earth element holmium placed on a surface of magnesium oxide. To write a bit, they used a scanning tunneling microscope, an instrument with an extremely fine tip that can work with individual atoms. A pulse of electrical current through the tip flipped the holmium atom’s magnetic orientation, switching the bit between 1 and 0.

Reading the bit back was the harder part. Popular Science explained that the team relied on an effect called tunnel magnetoresistance, and IBM also used a single iron atom placed nearby as a sensor to detect the holmium atom’s magnetic state. That’s the “detected indirectly” part of the result.

The researchers also showed that two holmium atoms placed about a nanometer apart could each be written and read independently. In the experiment, they stored two bits this way.

What It Could Mean for Storage

Although right now the product is pure research, the density of atomic-level storage could substantially alter our relationship with data.

You can already fit your entire music library onto a storage device the size of a penny. IBM’s technique would allow you to fit 26 million songs — Apple’s entire music catalog — onto the same area.

In the future, this development could have significant implications for everything from personal devices and business records to artificial intelligence.

The Catch

Don’t expect a single-atom hard drive any time soon. The experiment needed a scanning tunneling microscope and was carried out at very low temperatures. As physicist Pietro Gambardella of ETH Zürich, who wasn’t involved in the work, told Science News, warming the surface up to room temperature makes the atoms start to move around, which would scramble any data stored on them.

That’s why IBM described the work as basic research. The goal was to learn what happens to magnetic storage at the smallest possible scale, not to design a product.

What Came Next

The same Almaden lab kept pushing at the atomic scale, and the work moved from classical bits toward quantum ones. In October 2019, Lutz’s team published a paper in Science showing that they could control the quantum spin of individual atoms on a surface using a scanning tunneling microscope, making a single-atom qubit. They used titanium atoms on magnesium oxide, the same kind of surface used in the 2017 experiment, and could switch the qubit’s state in about 20 nanoseconds.

The storage industry, meanwhile, has kept squeezing more data into each square inch of disk using less exotic methods. The single-atom bit remains a proof of what’s physically possible, and a reminder of how much room is left at the bottom.