Dr Sander Otte, Delft University of Technology
From films to food ordering, our world is increasingly held in the digital sphere, this change in behaviour has led to a vast increase in data and that data has to be stored. Weíve mentioned before on the programme how big data means big warehouses full of the hard drives, energy supplies and the aircon needed to keep them cool.
But now researchers at Delft University of Technology, in the Netherlands, have come up with a new way to store data at thousands of times the densityÖ by using individual atoms. Claire Armstrong spoke with Sander Otte to hear howÖ
Sander - What weíve been able to do is to essentially make a hard disk where you can store data in the forms of 0s and 1s, just like you do on a regular hard disk, except that here the bytes are all encoded by a single atom. There is just one atom for each byte and then the position of that atom tells you whether the byte is a 0 or a 1. You can really compare it to I think itís called an abacusÖ one of those old fashioned calculators where you move beads around...
Claire - Yes.
Sander - Here you are moving the atoms around. And thatís exactly what you do and thatís how we store the data.
Claire - Oh, OK. Thatís quite a nice analogy actually - an abacus. And how are you actually doing this - what kind of atoms are you using?
Sander - We are using chlorine atoms on a copper surface and that was actually the big discovery here. We found that these chlorine atoms on this crystalline copper surface, which is perfectly flat, also forms a very smooth regular grid of atoms. And then in that grid of atoms, we put on, just too few chlorine atoms essentially and, as a result, there were some atoms missing so you have holes in the surface. Then it really looks like a sliding puzzle where one piece is missing and you can slide a piece towards a hole and thatís how you can move things around.
Claire - OK, wow!. So youíre really controlling things here at the atomic level?
Sander - Yep.
Claire - How do you move an atom?
Sander - So we this work with a so-called tunneling microscope (an STM). That technique has been around since the 1980s. It consists of a very sharp needle that scans over the surface and it kind of looks like a record player, and that needle is so sharp that it can feel the individual atoms on the surface. So it scans over the surface line by line and then if you put all of those height profiles together, you get your picture of where the atoms are. Once the picture is finished you can then take your STM back to whichever atom you would like to move and then use that same needle to move it around. Thereís a few different techniques to do this, so either you can use the atom to drag them or, in some cases, you can even pick up the atom and put them down. But, in this particular study, we found we just needed to bring down the tip and, as a result, we inject a current basically in the atom that we want move and that current is in the order of a microamp, which sounds like a very small number but itís an enormous amount of current for that single atom, and that causes the atom locally to heat up a bit and that gives it enough energy to make the jump to the neighbouring empty site where it then goes to.
Claire - OK, so by using this very sharp needle and the current you can push the atoms around and, by pushing them to a different positions, that means youíre storing different types of data. How fast can you read and write to this new hard drive?
Sander - Right. So there we come to the slightly less good news of this whole achievement, the read and write speed is still very slow. We actually didn't optimise to get to the fastest read or write speed yet so that in order to read the kilobyte we would need an hour, in order to re-write it we would need three hours. So that is almost ridiculous when we compare it to speeds that we normally have on our hard drive.
However, the dynamics of these atoms are ultrafast right. So, in principle, there is no limitation why this could not be sped up to let's say a megabyte per second as we see on a hard drive. However, I do recognise that there is quite a lot of technological barriers to be taken here, so it will definitely be a long time before we get there.
Data storage, to my opinion, is just an example here. Itís a demonstration of what we are able to do but I think there is a much more profound message here which is, we have been able to manipulate the world on a scale that was just impossible before. So we humans have now been able to build things on a scale of individual atoms and, if you think about it, that would eventually enable us to perhaps even tinker with how materials work and what kind of properties materials have if we could really choose ourselves where the atoms go, we could build all kinds of circuits maybe on the atomic scale.
I don't know what the possibilities will be in the future, but I am sure that it will be way cooler than just data storage. Data storage is just a bit of a lame example in that sense and by lack of any imagination, itís the best we can show but there will be much more than that.