Photonic neuron may compute a billion times faster than brain circuits

July 19, 2011 by Chris Emery, Princeton University

The project uses fiber-optic devices that make ultrafast calculations with photons of light instead of the electrons used by electricity-based computers circuits. (Photo by Frank Wojciechowski)
( -- The name of the project -- "photonic neuron" -- was catchy enough, but what really caught Mitchell Nahmias' attention was the opportunity to combine his interests in engineering and neuroscience.

Nahmias became one of seven Princeton undergraduate students to participate in a research collaboration between the University and Lockheed Martin, the aerospace and defense technology corporation, to produce fiber-optic-based computational devices that work similarly to neurons, but are a billion times faster.

"I'm an electrical engineering major, but I really like biology and cognitive science," said Nahmias, a member of the class of 2012. "This is a cool project, a really interesting confluence of a bunch of fields."

If the project is successful, the new technology could allow for that are capable of making nearly instantaneous calculations in life-or-death situations, such as locating a terrorist from a or deciding whether to eject a fighter pilot from a jet. It might also allow speedy processing of huge amounts of data, such as the video signals that currently guide the movements of robotic cars or scans of for clues to fighting diseases.

The research is led by Paul Prucnal, a Princeton professor of electrical engineering, and David Rosenbluth, a neuroscientist and principle engineer at Lockheed Martin's Advance Technology Laboratory, in Cherry Hill, N.J. It is funded by Lockheed Martin and Princeton's Stuart M. Essig '83 and Erin S. Enright '82 Fund for Innovation in Engineering and Neuroscience.

The project, which started in 2008, seeks to overcome the inherent speed constraints of electrical circuits, which are ultimately limited by the time it takes electricity to flow through wires. Instead of electrical wires, the team is using clear , through which information travels at nearly the speed of light. The "photonic" half of the project's name derives from photons, which are the fundamental unit of light, just as electrons are the fundamental unit of electricity. In conventional fiber-optic communications, photons speed information along great distances but are converted back to electrons once they reach a destination and the information needs to be processed. In Prucnal's lab, the processing occurs while the information is still encoded in light.

In addition to harnessing the ultimate speediness of light, the researchers are borrowing computational concepts used by the neural circuits that help humans and other organisms make ultrafast decisions.

Each neuron, whether in the brain or peripheral circuits of the nervous system, is connected to other neurons, which communicate through electrochemical pulses known as action potentials, or, colloquially, as "spikes." Based on the pattern of incoming spikes, a neuron decides whether to send out its own signal to convey information to the rest of the network. This function is the basis for neural computing.

The ability to make such decisions rapidly comes in handy in many situations. A gazelle being pursued by a cheetah, for instance, has to decide extremely quickly -- and correctly -- whether to dart left or right. A baseball player at bat has to decide to swing or not swing based on a number of cues that arrive a fraction of a second before the decision must be made.

The way that neural networks compute in do-or-die situations offers clues as to how computational devices based on light could function. "We are transposing learning, inhibition and other behaviors typical of neural processing onto fiber-optic circuits," Rosenbluth said. "But I don't think of it as trying to reproduce something in the brain. It's a hybrid between the analog computing done in the brain and the purely digital systems used by most computers."

When Prucnal and Rosenbluth first began talking about the possibility of studying blending fiber-optic signal processing and neuroscience, they noticed that although the mathematical equations used to model neural and fiber-optic networks used different variables, they were very similar in their overall formulation.

"We put the equations side-by-side and it was really an 'aha!' moment for us," Prucnal said. "It was pretty exciting that it might actually work."

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5 / 5 (8) Jul 19, 2011
So many words an so little content! How do they simulate neuronal activity with their optic fibers? How many neurons can they simulate at the same time? At what speed?
not rated yet Jul 19, 2011
Well, notice that the word 'defence' is used as a citation... so I'm sure at least some of this information is classified. However, the speed is mentioned in that it's a billion times faster than a neuron. That's enough to give me pause.
4.5 / 5 (48) Jul 19, 2011
Positronic net anyone?
3.7 / 5 (3) Jul 19, 2011
What will humans be good for then? Humans will distrust each others even more now that a computer is smarter than a human brain.
What are humans to do when everything is handled by super super fast photonic neurons.
We will become irrelevant quite soon.
1 / 5 (2) Jul 19, 2011
Actually this concept is consistent with organization of human brain. By recent studies neural solitons are sound waves supported by electrochemical activity of neural cell membranes. At the case of neurons of vertebrates the soliton character of spike propagation is enforced by internal structure composed of microtubules in analogous way, like inside of modern hollow-core optical cables. Maybe the artificial W.I.K.I brain from famous I, robot movie isn't the matter of so distant future.

BTW I wrote about optical fiber model of human consciousness many times here and I was always downvoted for it heavily. You can find more details about it at my blog.
5 / 5 (1) Jul 19, 2011
I agree with hb about the lack of information. I think the concept here is severely lacking explanation - and I don't think that has to do with whether it's classified or not.

My best guess is that the billion number they're throwing out is based on the speed of electrochemical signal relays in the brain vs. the cycle time of UV light.

Supposedly, based on the limited info we have, he's saying that one of these 'photonic neurons' would calculate in the neighborhood of 10^16 times faster than an entire arm chip.

I hate to be pessimistic...but show me the money or go home. Give me an experiment to show the basic principle works.

I seriously think this thing is an idea, with theoretical numbers thrown out, with no regards to real world performance. That said, I would love to be wrong. Theoretically, a computer chip could also run incredibly fast...but you'd need a very specific, impractical setup.
1 / 5 (1) Jul 20, 2011
Positronic net anyone?

@FrankHerbert: Now there's an odd form of anachronism. Aren't you afraid of the Butlerian Jihad?

P.S. Am I the only guy around here who reflexively down-votes anybody who whines about getting down-voted?
not rated yet Jul 20, 2011
Positronic net anyone?

@FrankHerbert: Now there's an odd form of anachronism. Aren't you afraid of the Butlerian Jihad?

P.S. Am I the only guy around here who reflexively down-votes anybody who whines about getting down-voted?

Depends on the situation. A lot of people are downvoted for god knows what reason. Sometimes it's just a well put comment that someone happens to disagree with. A lot of the time it's because some commentators are humorless aholes. It pisses me off when people are downvoted innappropriately, and I'll put a comment for everyone to uprate an innappropriately downrated comment - even if it expresses and opinion I disagree with - as long as it is well supported.
not rated yet Jul 23, 2011
Positronic net anyone?

@FrankHerbert: Now there's an odd form of anachronism. Aren't you afraid of the Butlerian Jihad?

Heretical Thinking Machines!

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