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Optical Computer Prototype

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Re: Optical Computer Prototype

#21

Post by dogma1138 »

mentos wrote: post #20
dogma1138 wrote: post #13

Earlier quoted context omitted.

It's not that easy to define because were talking about semi-conductors after all;) They don't move at a constant speed like say in a conductor (which isn't the case either because electric field causes resistance e.g. eddy currents, but lets say a super-conductor) You have quite a few concepts with semiconductors primarily saturation velocity (which in most cases is the peak velocity, but not necessarily attained in…

So does this imply an opportunity to improve computing speed by 2997?

No because the speed of the components with the current designs is still limited by the switching speed of the masking matrix. And in any case you will still need to transform photons back to electrons twice. The speed of electrons or EM wave propagation vs photons isn't a player in why photonic computing might be better. The ability to encode more data into the photons, a much more power efficient and inherently parallel design are.

Also because light has much more shorter wavelength than "electricity" electromagnetic waves in conductors (kilometers vs nano-meters) you can have a much higher throughput with light even if you use it to replace the carrier wires in electronics (which is what Intel is working on they want to keep electronic switching but make all carriers photonic).

https://en.wikipedia.org/wiki/Speed_of_electricity

Re: Optical Computer Prototype

#22

Post by benp84 »

mentos wrote: post #10
dogma1138 wrote: post #7

Earlier quoted context omitted.

Electrons have mass they can't move at the speed of light. Photons also have other nice properties such as wavelength which open a whole suit of possibilities e.g. like having a logic gate which can operate in different mods based on the wavelength and polarization of the light. While this is technically possible with electronics as well by setting a different voltage limit it's much more effective with photonic comp…

What fraction of the speed of light are electrons moving at in the most advanced silicon chip we have? Trying to understand how much speed is left on the table for us to pick up in serial processing?

Light moves 3*10^8 m/s in a vaccuum, which is 7.5cm per clock cycle of a 4GHz processor. The processor is about 2cm wide, so not much room for improvement I figure.

Re: Optical Computer Prototype

#23

Post by mechagodzilla »

jjoonathan wrote: post #19
imaginenore wrote: post #16

Earlier quoted context omitted.

Today's computers are very slow. Try modeling something complex, let's say 1 billion water molecules interacting. Then realize that 1 billion molecules is orders of orders of magnitude far from modeling a cup of water.

> 1 billion molecules is orders of orders of magnitude far Understatement. There are 50 trillion atoms in a cell, 50 trillion cells in a human body (give or take an order of magnitude or two for definitions and caveats). Furthermore, big swaths of chemistry/biochemistry are inherently quantum mechanical (classical mech + E&M doesn't explain why molecules snap into little geometric shapes, let alone how those shapes i…

Right, but they didn't build an optical computer that is even close to competitive with something like this:http://www.hotchips.org/wp-content/uploads/hc_archives/hc26/...

Re: Optical Computer Prototype

#24

Post by ajuc »

dogma1138 wrote: post #15
ajuc wrote: post #12

Earlier quoted context omitted.

Information we move around using electrons moves much faster than any single electron - because electrostatic field changes move at speed of light obviously, so the electrons at the end of wire start moving as soon as the electrostatic field change gets to it. You don't have to wait with processing for the electron from the beggining of the wire to get to the end? So, the difference between photons and electrons spee…

I didn't say that we need to move electrons (although we do for some things like Flash Memory), but you are confusing simple wave propagation in conductors with electron mobility in semiconductors which is quite a bit more complicated. You also need to remember that when we talking about waves then the wavelength ties directly to your data throughput, and with electrons the wavelength in conductors at say a frequency…

Yeah I was thinking about conductors, didn't realized it's different in semiconductor.

Regarding the wavelength - it's another of these things I never quite understood about physics. I've been told that every particle can be thought of as a wave with a frequency, and that it corresponds to the energy of the particle. Photons have lower energies than electrons or protons, so the wavelength of electrons should be shorter, not longer?

Re: Optical Computer Prototype

#26

Post by dogma1138 »

ajuc wrote: post #24
dogma1138 wrote: post #15

Earlier quoted context omitted.

I didn't say that we need to move electrons (although we do for some things like Flash Memory), but you are confusing simple wave propagation in conductors with electron mobility in semiconductors which is quite a bit more complicated. You also need to remember that when we talking about waves then the wavelength ties directly to your data throughput, and with electrons the wavelength in conductors at say a frequency…

Yeah I was thinking about conductors, didn't realized it's different in semiconductor. Regarding the wavelength - it's another of these things I never quite understood about physics. I've been told that every particle can be thought of as a wave with a frequency, and that it corresponds to the energy of the particle. Photons have lower energies than electrons or protons, so the wavelength of electrons should be short…

You've mixed and matched some of the stuff, leave wave-matter duality aside. You can treat it as any other wave in that regards best analogy will be acoustic waves because they are very simple. http://farside.ph.utexas.edu/teaching/em/lectures/node102.ht...
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