61 comments

[ 0.27 ms ] story [ 743 ms ] thread
Is there a single person here interested in photonic computing that wants to explain to the class if there's any "there" there?
Not an expert in the field but it seems to me the key points are.

Generating any wavelength. (this article)

Accurately measuring wavelength. (otherwise there's no information benefit to arbitrary wavelength generation)

Wavelength insensitive holographic gates. (If they work on that frequency, and in a way that does not change the frequency) I don't know what properties such devices currently have

Assuming all of those, your ability to compute increases to your ability to distinguish wavelengths.

You could theoretically calculate much more in a way you could never detect, but then you get into some really interesting tree falling in a forest issues.

The short answer if there is any "there" there for photonic computing is no, maybe.

You need to understand quantum physics[3,2]. For example, photonic computing, photonic logic does not have a switch equivalent as semiconducting (CMOS transistor) or superconducting (Josephson Junction JJ) but we have a photonic Mach Zener interferometer (MZI) and a photon detector.

Photonics and superconducting electronics is always going to be much larger in size (and therefore more expensive) than semiconductors build from few atoms.

In quantum physics photonics we have advantages like quantum impedance, you can replace wires with photon transmitters and photodetectors and thus switch with only a few photons instead of large numbers of electrons.

With photonics you can have billions of cheap low power data channels instead of high power wire bundles. But MZI as JJ will probably always be a few orders of magnitude larger than transistors so switching is not going to be better, but interferometry is.

Shorter answer still: just low power communications and information processing yes, computing no.

Bulk CMOS manufacturing is still cheaper than all the alternatives we have discovered or invented, until we learn to manufacture atom by atom or compute with single photons or electrons (also dependent on molecule by molecule self-assembly), we will stay with CMOS and Moore's law.

Just listen to David B. Millers[1] lectures [2], his lectures are a shortcut to reading all his papers[2] that explain it all, especially [3].

Email me, I'll give you a private lecture.

Your question's anwer is/was a summary of our whole lives research [4]:

[1] https://appliedphysics.stanford.edu/profile/35

[2] https://www.youtube.com/@davidmillerscience

[3] Attojoule Optoelectronics for Low-Energy Information Processing and Communication https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7805240

[4] Wafer Scale Integration Free Space Optics Computing https://www.youtube.com/watch?v=vbqKClBwFwI

Cool, can I get a "proper" yellow diode laser from this? What's the efficiency look like?
What if I like magenta? Or brown?
can they do microwave?

if you do the exact right color you can make certain things melt very precisely.

Everyone talking about magenta and brown, but you can see an illusory color right now even without lasers! https://dynomight.net/colors/ behold, some kind of hyper-turquoise
FYI if you get ocular/retinal migraines like me then the exercise in this article might be a bad idea.
I worked with a brown laser when I was in grad school. It made a couple of brown spots on the wall by accident.
Are you sure you weren't just squeezing a dispeptic mouse too hard?
Well this explains tripping on acid a little bit
very interesting, its quite striking, now I'm even more curious how this compares with the lasers.
Any day that I learn something new about color is a good day.

Here's my favorite color factoid: There is no such thing as monochromatic pink. You have to make it by combining the two ends of the visible spectrum: somethung reddish and something violet-ish. So that means there is no pink in a rainbow, strictly speaking.

> Weird stuff will happen, but stay focused on the dot. Blink if you must. It takes one minute and it’s probably best to experience it without extra information i.e. without reading past this sentence.

well that was a waste of fucking time

i just see cyan on the first one, seems like an exaggeration if anyone is expecting to see 'new' colors
Can each device vary the color or is it fixed based on how it’s built? Seems the latter?
Very cool stuff. I regret wasting my life in software when I see other fields still doing interesting work.
The "shrinking" circle: I did as asked and clicked the image to see the animation. I saw no shrinking. My eyes did fatigue and I saw the border between the red and green become a blurred gradient.

What should I have experienced?

You have to not blink too much or it resets the effect. After about a minute, the intense blue shows up around the red. And I say that as a man who has yet to see anything in a Magic Eye poster after a half century of what some would call life.
I also lack stereopsis- those posters are always just noise to me. I always wonder whether some of these visual tests only work on those with normal stereo perception.
Would I finally be able to see bright brown?
since the light range is so high, technically speaking as the technology improves does that mean we could end up sending petabytes a second over a single fiber optic core?
That's most certainly good news (depending on the final cost) for ion trapping quantum computing - the wavelength of the laser they require to trap an ion depends on the molecule chosen, and most setups are expensive, finicky and difficult to calibrate, or sometimes messy if it's a dye laser.
I wonder if this is a nuclear proliferation risk--could it be used for AVLIS/SILEX?
> When it comes to information transfer and processing, light can do things that electricity can’t. Photons — particles of light — are far zippier than electrons at working their way through circuits.

Electrons themselves don't move at the speed of light, but information transfer (i.e. communication) via electrons does happen close to the speed of light.

A subtle, but important, distinction that's often misunderstood and means computational performance gains would probably come from bandwidth, not latency.

In electric circuits, information is transmitted through the electric field, which itself is close to the speed of light.
About 0.6c for cat6 cables, different types of cables can be slightly faster. Speed of light in fiber is also 0.6c due to the refractive index of the core.
> but information transfer (i.e. communication) via electrons does happen close to the speed of light

Speed of light in the medium, not speed of light in vacuum.

My first thought is this will be used as a weapon to bypass protections against specific wavelengths
(comment deleted)
Just read the article and didn't see anything about building an actual laser… what details the article has (and its scant) its seems they took a fluorescing layer and sandwiched with a color wheel and added the additional wiring and control circuitry… (Obviously more nuanced and interesting physics but still…) cool and practical, but not a diode and definitely not a laser… I could be wrong and would love to be!

… now, if that setup could be drawn out into a fiber laser as cladding with a wide spectrum neural amplifying core (if such a material exists) that could maybe be something idk

I don't know to much about photonics but if they ever figure out the boolean algebra and register storage it would be really cool. You have 1 photo cpu core but just use different wavelengths for different threads running in the core. I am sure its way more complex than that but articles like this make you dream about how much we don't know
I'm excited for new displays where instead of RGB primaries that can only show a triangular subset of possible colours, we have dynamic primaries that can combine to show almost any colour.
0.1nm please. It's x-ray lithography time!