WHAT if “we can arrange the atoms the way we want; the very atoms, all the way down”? So asked the physicist Richard Feynman in an influential 1959 lecture called “There’s Plenty of Room at the Bottom”. This manipulation would mean that information, like text, could be written using atoms themselves. Feynman predicted that the entire “Encyclopædia Britannica” could be written on the head of a pin.

Three decades later, a group of scientists at IBM managed exactly that. They were able to write the firm’s name using 35 xenon atoms resting on a sheet of nickel—the first demonstration of precise atomic placement. Individual atoms, though, tend to jiggle around. They jiggle less at lower temperatures, so to keep the atoms in place, the researchers cooled them to -269ºC, just 4ºC above absolute zero, the coldest temperature physically possible. This was so costly that writing more than three letters did not make sense.

Now a team of researchers led by Sander Otte at Delft University of Technology, in the Netherlands, have done better, potentially paving the way for large-scale storage at the atomic level. Instead of three letters, they managed to store an entire paragraph of text (about 1 kilobyte of data). And the memory they used proved stable, in later experiments, at temperatures of -196ºC. That may not sound particularly balmy, but it can be achieved with liquid-nitrogen cooling, which is much cheaper than the liquid helium used by IBM.

The team stored their information not by writing letters with atoms, as IBM did, but in a binary code. They covered a sheet of copper with chlorine atoms, a process in which the chlorine atoms naturally form a lattice above the copper. But the team used only enough chlorine to cover five-sixths of the copper surface. The lattice therefore contained plenty of “vacancies”—spaces in which chlorine atoms could be present, but were not. Thanks to the bonds between the atoms, the lattice proved to be much more stable than the lone atoms used by IBM.

The team used pairs of one atom and one vacancy each to encode bits of information. They were able to write and rewrite the memory by sliding the atom within each pair back and forth. To do this, they used the probe of a scanning tunnelling microscope (STM), the same device IBM had used in their experiment 26 years earlier. Eight bits were arranged together to form one byte, which is enough to encode a single letter in the standard computer scheme used to represent text.

The pockmarked lattice was stable enough that the team was able to build 1,016 atomic bytes in an area that measured just 96 nanometres by 126 (an HIV virus, for comparison, is about 120nm across). That works out to an information density of 78 trillion bits per square centimetre, which is hundreds of times better than the current state of the art for computer hard drives.

The high density achieved by this kind of atomic storage could—some day—expand the memory capacity of phones, computers and data centres. But two further problems must be solved. It would help if the atoms could be made stable at room temperature. And, for now at least, the process is achingly slow. Dr Otte reports read and write speeds of 1-2 minutes per 64 bits. He reckons he could boost those speeds drastically, to about a million bits per second. But that is still thousands of times slower than modern hard drives.

Still, it is an impressive illustration of the advancing state of the art. And what did Dr Otte choose to inscribe on his atomic tablet? Naturally, two paragraphs of Feynman’s speech. Apparently, we can arrange the atoms the way we want.