[HN Gopher] GHz spiking neuromorphic photonic chip with in-situ ...
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       GHz spiking neuromorphic photonic chip with in-situ training
        
       Author : juanviera23
       Score  : 109 points
       Date   : 2025-08-04 11:21 UTC (11 hours ago)
        
 (HTM) web link (arxiv.org)
 (TXT) w3m dump (arxiv.org)
        
       | rf15 wrote:
       | Appreciating that not everyone tries to optimise for LLMs and we
       | are still doing things like this. If you're looking at HN alone,
       | it sometimes feels like the hype could drown out everything else.
        
         | danielbln wrote:
         | There is massive hype, no doubt about it, but lets also not
         | forget how LLMs have basically solved NLP, are a step change in
         | many dimensions and are disrupting and changing things like
         | software engineering like nothing else before it.
         | 
         | So I hear you, but on the flip side we _should_ be reading a
         | lot about LLMs here, as they have a direct impact on the work
         | that most of us do.
         | 
         | That said, seeing other papers pop up that are not related to
         | transformer based networks is appreciated.
        
           | larodi wrote:
           | Thank you, brother. Besides not all that goes in HN is
           | strictly LLM, really dunno why the scare.
        
         | karanveer wrote:
         | I couldnt agree more.
        
       | msgodel wrote:
       | It's just a single linear layer and it's not clear to me that the
       | technology is capable of anything more. If I'm reading it
       | correctly it sounds like running the model forward couldn't even
       | use the technology, they had to record the weights and do it the
       | old fashion way.
        
         | roflmaostc wrote:
         | Would you have discredited early AI work because they could
         | only train and compute a couple of weights?
         | 
         | This is about first prototypes and scaling is often easier than
         | the basic principle.
        
           | msgodel wrote:
           | Is this actually capable of propagating the gradient and
           | training more complex layers though?
           | 
           | A lot of these novel AI accelerators run into problems like
           | that because they're not capable of general purpose
           | computing. A good example of that are the boltzman machines
           | on Dwave's stuff. Yeah it can do that but it can only do that
           | because the machine is only capable of doing QUBO.
        
             | roflmaostc wrote:
             | For inference we do not care about training, right?
             | 
             | But if we could make cheaper inference machines available,
             | everyone would profit. Isn't it that LLMs use more energy
             | in inference than training these days?
        
       | fjfaase wrote:
       | Nice that they can do the processing in the GHz range, but from
       | some pictures in the paper, it seems the system has only 60
       | 'cells', which is rather low compared to the number of cells
       | found in brains of animals that display complex behavior. To me
       | it seems this is an optimization in the wrong dimension.
        
         | _jab wrote:
         | I suspect practicality is not the goal here, but rather a proof
         | of concept. Perhaps they saw speed as an important technical
         | barrier to cross
        
       | khalic wrote:
       | A lot of unrigorous claims for an abstract...
        
       | kadushka wrote:
       | Maybe try simulating the algorithms in software before building
       | hardware? People have been trying to get spiking networks to work
       | for several decades now, with zero success. If it does not work
       | in software, it's not going to work in hardware.
        
         | vessenes wrote:
         | This seems to work in hardware, per the paper. At least to 80%
         | accuracy.
        
         | good_stuffs wrote:
         | >If it does not work in software, it's not going to work in
         | hardware.
         | 
         | Aren't there limits to what can be simulated in software?
         | Analog systems dealing with infinite precision, and having
         | large numbers of connections between neurons is bound to hit
         | the von Neumann bottleneck for classical computers where memory
         | and compute are separate?
        
         | juliangamble wrote:
         | "Zero success" seems a bit strong. People have been able to get
         | 96% accuracy on MINST digits on their local machine.
         | https://norse.github.io/notebooks/mnist_classifiers.html I
         | think it may be more accurate to say "1970s level neural net
         | performance". The evidence suggests it is a nascent field of
         | research.
        
       | cwmoore wrote:
       | Retina-inspired video recognition using light. Cool. May be a
       | visual cortex next year.
        
       | vessenes wrote:
       | Ghz speed video processing, even if we only get very basic
       | segmentation or recognition out of it, is probably crazy useful.
       | Need to face recognize every seat at a stadium?
       | 
       | Well, if you have enough cameras, 60,000 seats could be scanned
       | 250 thousand times a second. Or if you want to scan a second of
       | video at 60fps, you'd be able to check all of them at a mere 4
       | thousand times a second.
       | 
       | Anyway, good to see interesting raw research. I imagine there are
       | a number of military and security use cases here that could fund
       | something to market (at least a small initial market).
        
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       (page generated 2025-08-04 23:01 UTC)