IBM has been looking into the concept of what would be the ultimate in tiny memory chips. And like any good scientific research, it’s all down to a super-powerful microscope.
The study is based on a remarkably simple premise. The best way to produce a smaller memory chip (or in turn, to get more capacity on the same size) is to find the smallest possible thing that can exist in two different states and thus represent one bit of digital information. And if you’re looking for something small, why not use an atom?
The first fundamental problem with making that a reality is that the way to put an atom into one of two states is to control its electron spin. That lasts for a much shorter period than the electrical charge used in tradition DRAM or Flash memory.
That in turn causes a problem when using the microscopic power needed to measure the electron spin (and thus retrieve data). A standard scanning tunneling microscope (a microscope capable of distinguishing individual atoms) is too slow to measure such detail and keep track of the spin.
IBM has now used a pulsed-STM microscope to tackle the problem. This involved sending out a pulse to put the spin into a known state, then measuring the state shortly after. The researchers then repeated this process with increasingly longer gaps between the pulse and the measurement, until the point at which the effects of the pulse were no longer measurable.
As a result it’s now known that a single iron atom can be forced into a state and held there for around 250 nanoseconds (250 billionths of a second) before being refreshed. To put that into context a standard DRAM cell needs refreshing every 50 milliseconds (50 thousandths of a seconds).
This isn’t a solution, but rather a case of at least understanding the precise question and the scale of the task. There’s already been some progress made: the 250 nanoseconds retention was achieved by placing the iron atom near a copper atom (without this, the iron atom only held the information for around one nanosecond).
But I wouldn’t throw that “bulky” memory card away quite yet.