IBM Creates World's First Artificial Phase-Change Neurons (arstechnica.com)

An anonymous reader writes from a report via Ars Technica: IBM has created the world's first artificial nanoscale stochastic phase-change neurons and has already created and used a population of 500 of them to process a signal in a similar manner as the brain. Ars Technica reports: "Like a biological neuron, IBM's artificial neuron has inputs (dendrites), a neuronal membrane (lipid bilayer) around the spike generator (soma, nucleus), and an output (axon). There's also a back-propagation link from the spike generator back to the inputs, to reinforce the strength of some input spikes. The key difference is in the neuronal membrane. In IBM's neuron, the membrane is replaced with a small square of germanium-antimony-tellurium (GeSbTe or GST). GST, which happens to be the main active ingredient in rewritable optical discs, is a phase-change material. This means it can happily exist in two different phases (in this case crystalline and amorphous), and easily switch between the two, usually by applying heat (by way of laser or electricity). A phase-change material has very different physical properties depending on which phase it's in: in the case of GST, its amorphous phase is an electrical insulator, while the crystalline phase conducts. With the artificial neurons, the square of GST begins life in its amorphous phase. Then, as spikes arrive from the inputs, the GST slowly begins to crystallize. Eventually, the GST crystallizes enough that it becomes conductive -- and voila, electricity flows across the membrane and creates a spike. After an arbitrary refractory period (a resting period where something isn't responsive to stimuli), the GST is reset back to its amorphous phase and the process begins again." The research has been published via the journal Nature.

Comments

Re:Inferior compared to my brain ...

[Rei]

Firing rates:
  * Human neuron: a couple hundred milliseconds
  * Chip: A couple dozen nanoseconds. (note: not microseconds!)

Size:
  * Human neuron: 4-100um on each axis
  * Chip: Currently 100nm square on a thin wafer, with a 90nm process; scalable to 14nm process.

Now, let's not get ahead of ourselves: they are far from demonstrating the ability to emulate a human brain here. But if they do manage to implement a system that properly models human neural activity, the potential to vastly outperform the brain should be obvious. The number of neurons that make up the human brain could be packed into a single layer chip a third of a square centimeter (times some factor to account for the interconnects) operating at ten million times the speed. To say nothing of the ease of integrating it directly with storage, networking, and general purpose computing hardware.

And there is motive to advance this field, too. Neural nets are starting to have direct consumer applications (leaps and bounds improvements in image recognition, image enhancement, bandwidth reduction, etc). And we're talking about neural net chips that could readily be sized as a coprocessor in a phone. If there's a market, they'll make them. And advance them with time.

No, IBM is far from having a "brain on a chip". But it's very interesting research, to say the least.