Communion Of Dreams

Well, another prediction arriving just about right on time.

In Communion of Dreams, one of the major plot points concerns the application of a new computing technology, based on what I call “Tholin gel” (a superconducting superfluid found on Titan which is not entirely understood by the scientists and engineers of the time).  The first generation of computers using this technology are just becoming available, and only a few are in operation.  They are superior to the computers based on a different technology, but have some limitations which I use for advancing the plot of the book.  The computers they are just starting to replace are the third (fourth? Hmm . . . I don’t remember) generation of thin-film computers, a very well understood and mature technology (at the time of the novel).

Well, guess what – we’ve just had a technological breakthrough with will lead to those thin-film computers:

How We Found the Missing Memristor

It’s time to stop shrinking. Moore’s Law, the semiconductor industry’s obsession with the shrinking of transistors and their commensurate steady doubling on a chip about every two years, has been the source of a 50-year technical and economic revolution. Whether this scaling paradigm lasts for five more years or 15, it will eventually come to an end. The emphasis in electronics design will have to shift to devices that are not just increasingly infinitesimal but increasingly capable.

Earlier this year, I and my colleagues at Hewlett-Packard Labs, in Palo Alto, Calif., surprised the electronics community with a fascinating candidate for such a device: the memristor. It had been theorized nearly 40 years ago, but because no one had managed to build one, it had long since become an esoteric curiosity. That all changed on 1 May, when my group published the details of the memristor in Nature.

Combined with transistors in a hybrid chip, memristors could radically improve the performance of digital circuits without shrinking transistors. Using transistors more efficiently could in turn give us another decade, at least, of Moore’s Law performance improvement, without requiring the costly and increasingly difficult doublings of transistor density on chips. In the end, memristors might even become the cornerstone of new analog circuits that compute using an architecture much like that of the brain.

Indeed.  Here’s a bit about how memristors work, and how they will be used (and why I chose the term “thin-film”), from Wikipedia:

Interest in the memristor revived in 2008 when an experimental solid state version was reported by R. Stanley Williams of Hewlett Packard.^[13][14][15] A solid-state device could not be constructed until the unusual behavior of nanoscale materials was better understood. The device neither uses magnetic flux as the theoretical memristor suggested, nor stores charge as a capacitor does, but instead achieves a resistance dependent on the history of current using a chemical mechanism.

The HP device is composed of a thin (5 nm) titanium dioxide film between two electrodes. Initially, there are two layers to the film, one of which has a slight depletion of oxygen atoms. The oxygen vacancies act as charge carriers, meaning that the depleted layer has a much lower resistance than the non-depleted layer. When an electric field is applied, the oxygen vacancies drift (see Fast ion conductor), changing the boundary between the high-resistance and low-resistance layers. Thus the resistance of the film as a whole is dependent on how much charge has been passed through it in a particular direction, which is reversible by changing the direction of current.^[8] Since the HP device displays fast ion conduction at nanoscale, it is considered a nanoionic device.^[16]

Memristance is displayed only when both the doped layer and depleted layer contribute to resistance. When enough charge has passed through the memristor that the ions can no longer move, the device enters hysteresis. It ceases to integrate q=∫Idt but rather keeps q at an upper bound and M fixed, thus acting as a resistor until current is reversed.

Memory applications of thin-film oxides had been an area of active investigation for some time. IBM published an article in 2000 regarding structures similar to that described by Williams.^[17] Samsung has a pending U.S. patent application for several oxide-layer based switches similar to that described by Williams.^[18] Williams also has a pending U.S. patent application related to the memristor construction.^[19]

There’s still a long ways to go before we see practical application of this technology.  But it will likely mean the same sort of radical change in electronics that transistors meant.  That should keep us going for, oh, say another 40 years or so (as the transistor revolution did), until we can discover and then start to use something akin to Tholin gel.

Jim Downey

(Via MeFi.)