Quantum computing for learning: Shaping reality both figuratively and literally

I’d like to document in snippets and thought-trains a little more of the story behind how my co-workers and I are trying to apply quantum computing to the field of intelligence and learning. I honestly think that this is the most fascinating and cool job in the world. The field of Artificial Intelligence (AI) – after a period of slowdown – is now once again exploding with possibility. Big data, large-scale learning, deep networks, high performance computing, bio-inspired architectures… There have been so many advancements lately that it’s kind of hard to keep up! Similarly, the work being done on quantum information processing here at D-Wave is ushering in a new computational revolution. So being a multi-disciplinary type and somewhat masochistic, I find it exciting to explore just how far we can take the union of these two fields.

Approximately 5 years ago, while working on my PhD at University, I started to have an interest in whether or not quantum computing could be used to process information in a brain-like way. I’m trying to remember where this crazy obsession came from. I’d been interested in brains and artificial intelligence for a while, and done a bit of reading on neural nets. Probably because one of my friends was doing a PhD that involved robots and I always thought it sounded super-cool. quantum_learning_1But I think that it was thinking about Josephson junctions that really got me wondering. Josephson junctions are basically switches. But they kind of have unusual ways of switching (sometimes when you don’t want them to). And because of this, I always thought that Josephson junctions are a bit like neurons. So I started searching the literature to find ways in which researchers had used these little artificial neurons to compute. And surprisingly, I found very little. There were some papers about how networks of Josephson junctions could be used to simulate neurons, but no-one had actually built anything substantial. I wrote a bit about this in a couple of old posts (from Physics and Cake blog):

I’d read about the D-Wave architecture and I’d been following the company’s progress for some time. After reading a little about the promise of Josephson junction networks, and the pitfalls of the endeavour (mostly because making the circuits reproducible is extremely difficult), I then began wondering whether or not the D-Wave processor could be used in this way. It’s a network of qubits made from Josephson junctions after all, and they’re connected together so that they talk to each other. Yeah, kind of like neurons really. Isn’t that funny. And hey, those D-Wave types have spent 8 years getting that network of Josephson junctions to behave itself. Getting it to be programmable, addressable, robust, and scalable. Hmm, scalable…. I particularly like that last one. Brains are like, big. Lotsa connections. And also, I thought to myself (probably over tea and cake), if the neurons are qubits, doesn’t that mean you can put them in superposition and entangled states? What would that even mean? Boy, that sounds cool. Maybe they would process information differently, and maybe they could even learn faster if they could be in combinations of states at the same time and … could you build a small one and try it out?

The train of thought continued.

From quantum physics to quantum brains

That was before I joined D-Wave. Upon joining the company, I got to work applying some of my physics knowledge to helping build and test the processors themselves. However there was a little part of me that still wanted to actually find ways to use them. Not too long after I had joined the company there happened to be a competition run internally at D-Wave known as ‘Apps Day’, open to everyone in the company, where people were encouraged to try to write an app for the quantum computer. Each candidate got to give a short presentation describing their app, and there were prizes at stake.
quagga
I decided to try and write an app that would allow the quantum computer to learn how to play the board game Go. It was called QUAGGA, named after an extinct species of zebra. As with similar attempts involving the ill-fated zebra, I too might one day try to resurrect my genetically-inferior code. Of course this depends on whether or not I ever understand the rules of Go well enough to program it properly :) Anyway… back to Apps Day. There were several entries and I won a runner-up prize (my QUAGGA app idea was good even though I hadn’t actually finished coding it or run it on the hardware). But the experience got me excited and I wanted to find out more about how I could apply quantum processing to applications, especially those in the area of machine learning and AI.

That’s why I moved from physics into applications development.

Since then the team I joined has been looking into applying quantum technology to various areas of machine learning, in a bid to unite two fields which I have a really strong feeling are made for each other. I’ve tried to analyse where this hunch originates from. The best way to describe it is that I really want to create models of machine intelligence and creativity that are bio-inspired. quantum_learning_2 To do that I believe that you have to take inspiration from the mammalian brain, such as its highly parallel, hierarchical arrangement of substructures. And I just couldn’t help but keep thinking: D-Wave’s processors are highly parallel systems with qubits that can be in one of two states (similar to firing or not firing neurons) with connections between them that can be inhibitory or excitory. Moreover, like the brain, these systems, are INCREDIBLY energy efficient because they are designed to do parallel processing. Modern CPUs are not – hence why brain simulations and machine learning programs take so much energy and require huge computer clusters to run. I believe we need to explore many different hardware and software architectures if we want to get smarter about intelligent computing and closer to the way our own minds work. Quantum circuits are a great candidate in that hunt for cool brain-like processing in silicon.

So what on earth happened here? I’d actually found a link between my two areas of obsession interest and ended up working on some strange joint project that combined the best of both worlds. Could this be for real? I kept thinking that maybe I wanted to believe so badly I was just seeing the machine-learning messiah in a piece of quantum toast. However, even when I strive to be truly objective, I still find a lot of evidence that the results of this endeavour could be very fruitful.

Our deep and ever-increasing understanding of physics (including quantum mechanics) is allowing us to harness and shape the reality of the universe to create new types of brains. This is super-cool. However, the thing I find even cooler is that if you work hard enough at something, you may discover that several fascinating areas are related in a deeper way than you previously understood. Using this knowledge, you can shape the reality of your own life to create a new, hybrid project idea to work on; one which combines all the things you love doing.

8 thoughts on “Quantum computing for learning: Shaping reality both figuratively and literally

  1. I agree to the point: “If you work hard enough at something, you may discover that several fascinating areas are related in a deeper way than you previously understood.”

    Also could you please comment on challenges at:
    1. Hardware design/Josephson junctions and improvements they still need to have for future growth of quantum computing.
    2. What kind of mathematical challenges are there in putting machine learning algorithms on quantum computer such as of D-Wave.

    Regards,
    Vijay

    • Hi Vijay, thanks for your reply.

      Firstly In response to your question about the hardware design and the Josephson junctions…

      The individual Josephson junctions and qubits on the D-Wave processors work really well. However, as with all integrated circuits, the more of these you put on a chip, the more you find that any tiny fluctuations or imperfections will accumulate in the processor as a whole. So the size of the processors that can be manufactured at the moment (~512 qubits) is partly related to how close you can get the fabricated components to their intended design specifications.

      As the fabrication process improves, the processor integration level will therefore increase. Currently integration limitation comes from issues such as uniformity of layers and defects in the materials, although I’d have to admit I’m not an expert on the fabrication side!

      Regarding your second question, we’ll be writing several in-depth posts on the machine learning algorithms that we are looking at in the next few months, so hopefully some of those will give insights into the mathematical challenges of machine learning using QC!

      • Great article! Like the passion you express, Physicsandcake. Sounds like you love working at D-Wave. I’m always pondering about what true AI will be like. When AI finally does emerge I wonder if it will shed new light on metaphysical aspects of consciousness? For example, ESP, remote viewing, etc. And, if it is a quantum AI, might it be able to communicate with other intelligences in parallel universes. My goodness, this is so wonderful to think about. Exciting times ahead! :-)

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  3. And here I thought I was the only person who had thought about a quantum neural network. Boy did you prove me wrong! This was an excellent post. I’ve also been wondering how Hinton’s deep neural network could be leveraged by the D-Wave computer. We should talk! :)

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