Superconducting processors get some competition?

EPFL and ETH (Switzerland) are undertaking a four year project named CMOSAIC with the goal of extending Moore’s law into the third dimension:

The project page is here

And here’s an IBM write-up of the effort

Also see here for a nice schematic of the device

“Unlike current processors, the CMOSAIC project considers a 3D stack-architecture of multiple cores with a interconnect density from 100 to 10,000 connections per millimeter square. Researchers believe that these tiny connections and the use of hair-thin, liquid cooling microchannels measuring only 50 microns in diameter between the active chips are the missing links to achieving high-performance computing with future 3D chip stacks.”

Just my personal opinion of course… but…. this seems like a case of fixing the symptoms rather than finding a cure. Will bringing a microfluidic angle into Moore’s law really help us out?

Why do we put up with this kind of heating problem in the first place? One could, for example, consider an alternative investment in the development of reversible, low disspation superconducting electronics.

I guess the project will be interesting just from a point of view of 3D manufacturing and incorporation of fluidics into microchips – this kind of technology could be indispensable for progress in areas such as lab-on-a-chip technology. But as far as raw processing power goes, this approach seems a bit like ignoring the elephant in the room.


Post-IOP-Talk thoughts

So I gave this talk last night entitled: Quantum Computing: Is the end near for the Silicon chip? It was an interesting experience. I’ve given talks of this size before, but I don’t think I have ever tried so cover quite so many topics in one go, and give so many demonstrations in the process. So with two radio microphones strapped to my waist, and 3 cameras recording the talk, I proceeded to enthusiastically extol the future potential for superconducting electronics technology, and warn about the limits of silicon technology. I gave an overview of superconductors for use in quantum computing, which culminated in a discussion of interesting applications in machine learning and brain emulation.

The main problem I had during the talk was that I wanted to stand in FRONT of the rather large podium/desk in order to talk to the audience, as I felt this would be a bit more personal (rather than ‘hiding’ behind the desk). However, the controls for the visualiser, (which is a camera pointing at an illuminated surface connected up to the projector so that the audience can look closely at objects you wish to show) were behind the desk, so I had to keep running backwards and forwards every few minutes to switch from visualiser -> laptop output. This was most irritating and is a really poor design in a lecture theatre. The control for the projector output really should have been somewhat more mobile.

The other moment of complete fail was when the large piece of YBCO stubbornly refused to cool to below 90K when immersed in the liquid nitrogen. Stupid smug piece of perovskite. I stood there for what seemed like hours, with over 80 pairs of curious eyes fixated upon my failing experiment, eagerly anticipating some badass superconducting action. And the damn magnet wouldn’t levitate. There was just way too much thermal mass in the YBCO block and its metal/wood housing to cool it quickly enough. I eventually gave up and swapped to the smaller YBCO piece, making some passing comment about physics experiments never working.

Anyway, those gripes over, the talk seemed to attract a lot of questions relating to the last 30% of the material I covered, namely the part about simulating the human brain and potentially building quantum elements into such machine intelligences.

Anyway I hope it inspired some of the younger members of the audience to consider working as scientists in these areas to be interesting career paths.

I’ll try and get the talk edited and put up on the web soon 🙂

Writing a cool lecture is hard. But rewarding!

I’m currently writing a lecture about…well I’m not quite sure what it is going to be about yet. It’s an IOP evening lecture, and I want it to be awesome.

It’s entitled: Quantum Computing – The end of the silicon chip?
For a start that’s a misnomer as Quantum Computing devices are still, for the most part, made on Silicon chips 🙂 But the idea is that there is a materials revolution in there as well as a shift in computational paradigm.

I want to do a slightly unusual style of lecture where I talk about lots of really cool stuff. I want to get some brains in there somehow so I’m going to talk about the applications of QCs to neural networks. I also want to get in there the idea of how you actually make integrated circuits, what is actually INSIDE your iPhone, and just how awesome the engineering that goes on to produce that kind of thing is. I have a hunch that there’s nothing on the National Curriculum about that kind of stuff. (There certainly wasn’t when I was taught at school). I also want to get some LN2 demos in there as schools always love this kind of stuff.

I’m actually not a great fan of the current demo that I routinely give to audiences of varying sizes. The format generally goes like: Low temp Physics -> Superconductivity -> JJ/SQUIDs -> Quantum Computing.

Why is this bad?

Well, one problem I find with this style of lecture is that you get onto the cool stuff (from my POV) at the end (hell, we make stuff colder than interstellar space and then make it quantum compute. We exploit the power of the multiverse, b*tches!) but in order to get to that bit you have to explain superconductivity, and in order to explain that you first have to talk about lots of low temperature experiments and properties of solids, liquids and gases, blah blah. So what actually happens is that you do all the LN2 demos at the start, and then the audience gets really bored at the end. I also just don’t think that superconductors have the same WOW factor that they used to. I give this lecture so many times and talking about things like High Temperature Superconductivity being cutting edge research just doesn’t do it for schoolkids anymore (it’s also not true). And they’ve all seen the floating magnet and the liquid nitrogen before. It’s sometimes embarrassing…

The second problem is that the EMPHASIS is all wrong. You shouldn’t try to entice kids into Physics by throwing liquid Nitrogen at them, putting balloons and flowers and bananas and *insert your favourite normally-at-room-temperature item here* into cryogenic liquids. It’s quite fun for them to watch at the time, but it’s actually quite psychologically deceitful. Believe it or not, physicists don’t actually dip bananas into cryogens as part of their normal working day.

In fact what we do is even cooler, and getting across a sense of why is much more difficult. But it is also a much more rewarding challenge. So…what I shall try to do is either play down the easy-but-somewhat-irrelevant demos, make the later stuff more awesome, or intersperse the demos through the talk somehow. I suspect I will implement a combination of the latter two.

I also think that these kind of lectures are not supposed to teach kids what we already know about Physics. We should teach them that there’s a lot we don’t know. That is what will probably make them want to be scientists in the future. So explaining the ideal gas law is all very well and good, but they can do that in class. By holding these research lectures, we should inspire and humbly explain that as a scientific community we really don’t know enough, but it’s a great challenge to face that unknown. To teach them that this is where we are stuck, and that’s why we need people like you guys sitting in the audience to ace your science classes now, and help us out in the future.

I’m probably going to blog about the progress of this as I write it. Hey, I might even get some more people attending! I’m thinking of doing a RI Christmas lecture style thing with lots of visuals, demos, audience participation, microscope connected to projector. etc. I’m going to try to get a volunteer to dress up in a cleanroom suit and bring him/her into the lecture theatre to illustrate the idea of humans+fab=bad…any takers? 😀

Quantum brains

I’m going to talk about quantum brains. But before I do, I have to take a bit of a philosophical detour. So bear with me and we’ll get onto the meaty quantum bits (qubits?) soon.

Disclaimer 1: This is a very general introduction article – it is probably not suitable for QIP scientists who may attempt to dispose of me (probably with giant lasers) for lack of scientific rigor…. *ducks to avoid flying qubits*

We need to think about what we are trying to build. Say we want to build a brain (in silicon, for arguments sake). Well, for a start that’s not really enough information to get on with the task. What we actually want is a mind in a box. We want it to think, and do human-like things. So we run into a problem here because the mind is a pretty vague and fuzzy concept. So for the purpose of this argument, I’m going to use Penrose’s definition of 4 viewpoints of how the mind might be connected to the physical brain, which is given in his book Shadows of the Mind, but I will summarise here for those who are not familiar with the definitions:

There are basically 4 different ways you can interpret the way the mind is related to the actual signals buzzing around and the physics going on in that wet, squishy 3lb lump that sits in your skull. Here they are:

(A) – The ‘mind’ just comes about through electro-chemical signals in the brain. You could fully reproduce a ‘mind’ in any substrate using standard computer providing you could encode and simulate these signals accurately enough. It would think and be conscious and self-aware in exactly the same way as a human being.

(B) – The workings of the brain can be simulated in exactly the same way as in (A) but it would never be conscious or have self-awareness, it would just be a bunch of signals that ‘seemed’ to be behaving like a human from the outside. It would effectively be a zombie, there would be no ‘mind’ arising from it at all.

(C) – There’s no way you can simulate a mind with a standard computer because there’s some science going on that creates the ‘mind’ that we don’t yet know about (but we might discover it in the future).

(D) – There’s no way you can ever simulate a mind because our minds exist outside the realm of physical science. Period. Even that science which we are yet to discover. (This is a somewhat mystical / spiritual / religious argument).

Interestingly Penrose goes for C – mainly because he believes that there are quantum processes occurring in the brain, and the quantum mechanics going on in there cannot be simulated using a conventional computer. So it’s not that we don’t understand the science yet, but we can’t build computers that are able to take that science into account (i.e. model the quantum mechanics correctly). Or can we… don’t we have, like quantum computers now?

Now back to the quantum braaains…

What do I think is the most exciting prospect for quantum computers? Forget factoring, what about building quantum brains? Note: I’m using the phrase ‘brain’ here in a rather unscientific sense to mean a large collection of interconnected agents – essentially a large neural network.

I am a supporter of (A) – which is a variant of the Strong AI hypothesis. That is, a human-level intelligence could be fully simulated on an alternate substrate using a standard, ‘classical’ computer and actually BE conscious and self-aware. However, with this point of view, one might wonder what a similar level of integration would be capable of if it could use some aspects of quantum mechanics as an integral part of its operation.

My viewpoint conveniently makes my argument for the further development of QCs pretty watertight. If quantum computers ARE required to simulate the human brain, (which I do not believe to be the case), then we should probably develop them anyway. If they are NOT required, but are believed (at least by some) to be fundamentally more efficient for certain computational tasks, then wouldn’t it be a cool experiment to make a brain which could harness that extra computational power? I mean… it would be a fundamentally different type of intelligence. Doesn’t that sound cool? Doesn’t that just make you smile and make the hairs on the back of your neck stand on end? Or maybe that’s just me…

Attentive readers may note that I have subtley disregarded option D here. That’s because D stands for Deepak Chopra, who is much better at explaining how QM ties in with that viewpoint than I am.

Quantum Neural Networks have already been explored theoretically. (See here, here, here for just a taste). I think very small QNNs could be realised experimentally at present. If they can be shown to work in principle, they can be scaled up and investigated further.

Adiabatic Quantum Systems based on the Ising model are perfect for this task. Their structure and behaviour resembles a spin-glass, which is mathematically equivalent to certain types of neural network. A spin glass can store patterns in ‘stable’ configurations of spins, just as the brain stores memories as patterns in configurations of the synaptic strengths between neurons (a simplistic model but it’s kinda the main point).

Of course there’s always the problem of decoherence – and it most likely will be a problem in large scale quantum systems. There’s probably some puddles of coherence around the place, maybe they overlap, maybe they don’t. No-one really knows. Could those puddles of local coherence provide any extra computational power? How connected (or perhaps disconnected) would they have to be? Can we design scalable solid state systems with larger puddles?

Again, that sounds to me like something we should investigate.

In conclusion

We should be able to simulate anything that the brain is doing (even if we need quantum computers). If the brain IS using large scale coherence in its operation, it shows us that it IS possible to build large scale coherent quantum systems (if nature can do it then so can we). This would be useful for all sorts of things, like simulating protein folding. In fact this would arguable be the best outcome. I kinda hope Roger Penrose is right…

However, I don’t believe he is right, as I currently believe the level of large-scale quantum coherent phenomena in the brain is very close to ZERO. But that means we can only IMPROVE the level by which quantum mechanics could be leveraged in brain-like systems, by building huge and densely connected NNs using quantum devices such as superconducting qubits. We can explore completely new territory in the building of intelligent systems…

Thus we have a win-win situation 🙂

In other words, QCs are cool and we should build them.
And we need more money *ahem*

Note: I argue this and a bunch of other stuff in my QC & AI lecture. Here is the link to my post about that

Disclaimer 2: This topic has also probably been debated to death and back on various places around the internet but it’s always good to exhume it once more for a guest appearance. In fact if I wasn’t feeling so lazy (and cold, the heating in here appears to be broken at the moment) I might have bothered to dig up some references. It’s also a useful place to send people to if they want to know my point of view on this.

EDIT: To perfectly illustrate both my points that a.) there’s loads of stuff on the internet + I’m lazy and b.) software systems are surprisingly intelligent already (WordPress helpfully pointed out the link for me) here’s some stuff that Geordie wrote about this a while ago:

Can an artificial general intelligence arise from a purely classical software system?

Media coverage, skew, and general not-in-the-Christmas-spirit ranting

Bah, humbug.

A little earlier I nonchalantly and lazily microblogged using the oh-so-professional channel of my Facebook status about something that slightly irritated me whilst watching the news. Here was what I wrote:

One attempted act of terrorism: Almost 24/7 news coverage. Thousands of scientific breakthroughs every day: Not even a few minutes of airtime. No wonder the general public feel isolated from science, in fear of technological advancement and generally depressed at the state of the world…

Anyway, seeing as the comment sparked quite an interesting conversation, I thought I’d relay these thoughts on this, my slightly more traditional soap-box haunt.

Obviously my comment pertained to the recent attempt to bring down a plane travelling from Amsterdam to Detroit. How much about this could there possibly be to report? Hours worth of television time, apparently.

It just depresses me that the news programs, day after day, cover crime, terrorism, war and political unrest as their main stories, then attempt to lighten this doom-riddled cake of hopelessness with a cherry in the form of a ridiculous human factor story about some family’s cat being rescued from a tree (or something equally banal). Earlier today I watched a story about freak weather in the UK – the seemingly important aspect of this being a woman who gave birth in an ambulance because it was stuck in the snow on a sliproad on the A14. Oh, and then there’s 10 minutes of football news!! If I were sat at a desk I would somewhat non-figuratively be slamming my head against it at this point. Luckily for me I’m on a sofa.

I’m not just going to have a long rant here about what I think the news SHOULD be covering, I think that much is pretty obvious from my list of interests ~superconducting flux qubits, yey!~ <-excuse the voices in my head.
Moreover, I'm wondering: What can we actually DO about it?

During my time in a University setting, I think I've only once been invited to a seminar by a person from the Press (in this case it was Radio 4). I think that the press just do not engage enough with scientists. There is so much cool research just waiting to be explored and popularised. There is also a large body of enthusiastic, young PhD students who would be willing to talk about what they are doing, which would not only help popularise their respective subjects, but also break that 'mad professor / scientist' stereotype which seems to still be hanging around a couple hundred years after it was actually representative.

However, until the 'media approaching scientists' kind of thing reaches a critical mass, it will be up to the scientists to shout louder and more ingeniously to make people take note. It will be up to them to chase down the media opportunities.

And I believe that there is a somewhat insidious problem here – primarily that it's not considered a worthwhile activity amongst science/engineering peers to communicate and popularise your research. Carl Sagan et al. are very much the exception rather than the rule. Popularisation is certainly not taught alongside science, or encouraged, even though there are lots of external grants available for this kind of thing. We rely on the rebellious defector amongst academics to propagate the enthusiasm. Instead, we should be supporting those who wish to act as spokespeople for their research.

A lot of media types are also looking for the ‘scare story’ angle. They will try every trick on the book to hype the negative angle of your research, especially of you are working in disruptive or controversial technology areas. I think that academics should be trained to answer media questions a bit like politicians: Get across the positive impact at all costs (short of actually, you know, lying..). And for goodness sake don’t mention Skynet. Or nano greygoo*ahem* tech. It’s ‘submicron’ or ‘molecular’ engineering, guys!

Ultimately, the goverment hands out the money to the funding councils, and therefore if we as scientists aren’t in the forefront of their minds (I mean look, we’re competing with the NHS, the education system, the war in Afghanistan, etc….), if they don’t see our science and go “Wow, you know – that’s not only the future of our country, but it’s actually pretty interesting too”, then funding for our research will indeed be cut.

So go out there and tell people that your research, be it Physics or whatever, is awesome. In any way you can. Ignore anyone who tells you that it isn’t worthwhile. And if you do it right – if you do it *really* right – then those people might just mention it to their friends the next time they have tea and cake 😉


Note: On this topic with a slightly more transhumanist slant, inspired by the conversation, Stuart has also written a blogpost.

Merry Christmas by the way people.

A flurry of interesting preprints…

My pick of interesting recent ArXiv papers…
So much to read, so little time!

Robust Entanglement in Anti-ferromagnetic Heisenberg Chains by Single-spin Optimal Control

Quantum System Identification: Hamiltonian Estimation using Spectral and Bayesian Analysis

Hierarchical Genetic Algorithm Approach to Determine Pulse Sequences in NMR

Efficient creation of multipartite entanglement in flux qubits

Spin Systems and Computational Complexity

Algorithmic Technique for Decomposing Unitary Operations in NMR Quantum Computation