Quantum computers are increasingly being touted as the key to major breakthroughs in medicine, transport, and greener energy. One expert even believes that – if we are lucky – they will elevate humankind’s comprehension of reality.
“We’re going to collectively need to believe the answer that is coming out of a quantum computer that can’t be simulated in any other way.” This statement was made recently by Tony Uttley, president and chief operating officer of Quantinuum, one of the companies leading the charge towards the potentially life-changing technology.
This felt like a bit of a contradiction in terms. How could something underpinned by the science of quantum mechanics and sitting on the cutting edge of technological development essentially boil down to an article of faith?
Keen to find out more, I reached out to Quantinuum. Uttley’s colleague Ilyas Khan, the company’s chief executive officer, agreed to sit down with Cybernews and shed some light on a vastly complex subject that, to paraphrase his own words, could end up at the heart of the greatest technological breakthrough since the Industrial Revolution.
Regarding Tony Uttley’s comment, it seems that we’re going to have to take a lot of what quantum computers are telling us on trust or faith – is that the case?
The context of the trust is very clearly divided into two areas. Neither of them are mystical or confusing or require cryptocurrency-type faith. A reminder: quantum mechanics is certainly the most tested of sciences in the last 70 or 80 years. David DiVincenzo, a very distinguished physicist, came up with seven criteria [in 2000] that essentially constitute a working quantum computer.
So at the very base level our ability to trust any device – your watch, my telephone, anything – requires some faith, but you've got to start with the mechanics. You trust a watch because the mechanics work. I think DiVincenzo's criteria are the starting and end point for our ability to verify that something is in fact a quantum computer. The language that he used is accessible and doesn't require a degree in quantum physics or computer science [to understand it].
"Our ability to trust any device requires some faith, but you've got to start with the mechanics."Ilyas Khan, CEO of Quantinuum
So let's just assume that one goes beyond that: and Tony's commentary was, I think, assuming that one has. I said there were two clear silos: the question of trust or faith in cybersecurity versus [that] in computing. The cybersecurity one is germane and let me touch on that.
Most people, when they think about quantum, they think about attack, are they going to hack everything? A quantum computer provides the ultimate defence against a quantum attack. And so if we think about any cybersecurity key, it is a concatenation of algorithms that jumbles up information: that algorithmic approach to seeding keys is the bedrock of everything that's going on in cybersecurity, and has been for many years.
The problem is that despite lots of promise, quantum keys – non-deterministic jumbling up – have never taken off. The reason is – if you speak to somebody at the NSA [National Security Agency] – quantum devices have never been verifiable: they're a black box. Despite being around for 20-odd years, the market share for cybersecurity quantum random number generators is infinitesimally small.
The reason is if you sent one of those devices to a government installation, there would be three things that the boffins would say. The first is: this is not accountable, I do not know what's going in there – I'm not touching it. Secondly, if you walk past with a magnet or there's a little tremor somewhere in Kilimanjaro, there's no way of knowing whether the quantum effect is maintained. Lastly, report after report has found that there actually is regression in these things – they're not really random. The reason is they don't comply with all of the loopholes that have been identified by quantum physicists when you generate such things.
What Tony is referring to is when you have a quantum computer rather than a quantum random-number generator, and you use the qualities of entanglement and superposition, you can implement something called a Bell Test. This was thought up by a physicist in Northern Ireland in the early ‘60s and then experimentally proven many times through the ‘80s and ‘90s and thereon.
The California Institute of Technology came up with this way of verifying that if a stream of entropy, or randomness, is generated from a quantum computer, then you can verify by implementing a Bell Test that this is indeed quantum – and because of that it is entirely non-deterministic. Nobody knows why that is the case, but when you tap into it, there is no algorithm, it is patternless: and this has been written about and proven for many years. It is one of the bedrocks of quantum mechanics.
What Tony was referring to was with a quantum computer there's no need for trust – you can implement a Bell Test. You, the user – rather than the person who is trying to flog you something. And therefore you cut out the degree to which you need to trust anyone.
Could you clarify what you mean by non-deterministic? Sandbox AQ’s CEO, Jack Hidary, spoke about Einstein not liking quantum because it appeared to be probabilistic. Does this tie in with that?
Yes, exactly so. Einstein died not understanding two things. One was the non-deterministic. Einstein's greatest discovery that we know about, relativity, is based on the fact that if you go from starting conditions you can work out what the end is [drops a piece of Bluetac on desk as an example]. The weight of the Blue Tac, the environment I'm in, there's no wind, etc. So at a fundamental level – whether its Newtonian mechanics or Einsteinian – things are deterministic.
I'm a cricket fan: if somebody hits the ball and it’s travelling up in the air at a velocity, miraculously, human beings are equipped to catch the ball – how do we know where to go, when and how? Whether it's intuitive or instinctive, or whether it's something that is worked out, the world around us is non-probabilistic. It is deterministic – there's one outcome, I throw the ball from here, it will go there.
What Jack was probably referring to is when you get down to the quantum level, at which we examine atoms and photons and electrons, the world is not deterministic. There's a probability that this might happen, or that might. And the Bell Inequality is the ultimate proof that entropy, change, randomness if you wish, taken from nature does not need an algorithm, so therefore it can't be hacked.
In 2019, Google said they had done something that can't be done using a classical computer – a quantum computer had “achieved supremacy.” Unpacking this is relatively easy: it's about trying to understand whether a quantum computer is doing something that is better than or cannot be done by existing computers. That claim was attacked by many people, including IBM. Subsequently, a supercomputer had actually done what Google said could only be done using a quantum computer. I don't think Google were misleading anybody – I think at that time they thought they had found something which couldn't be done. Now that something was very arcane. And so the rest of us in the real world were like: “Well, where does that get us?”
So there has been this debate for a while, which is how and when can we do something that is practically and verifiably not currently possible using a classical computer and is useful: something you can actually solve problems with. And there is very little evidence that anything like that has happened up until now.
What you can reasonably infer from what Tony said is: what happens when you are doing stuff that is quantum but can't be compared?
What’s your benchmark for assessing results from a quantum machine, in other words?
That's right. And we believe at Quantinuum that informed consensus will happen, because now the scaling of quantum computers is an engineering not a science challenge. The language around what has and hasn't yet been done will become more apparent and clear – just as it has with all industries. What Tony was essentially saying is: at the moment the only way of verifying is comparing with classical, but at some point when we get beyond what classical computers can do, the verification will become something that the world will adopt. There are people, especially in the UK and US, who are maniacally focused on this. The National Institute of Science and Technology [in the US] has a team doing nothing but.
So you are saying that when this progresses, we won’t need to rely on classical computers, because the results will be self-evident?
Well, there will be a class of problems, tasks, which become self evident: when I put water into my hot water kettle, it's self-evidently boiling. There will be things like that: material designed to sequester carbon will be testable because it will sequester carbon.
I think the interim before we get to that – where things have quantum advantage, that's the terminology that people use – I think that's the area where there's a degree of opacity that will be lifted as practitioners publish papers. There will be an informed consensus and we won't have to guess.
"Quantum computing is not merely a new technology, but an Industrial Revolution for the first time since the end of the 19th century."
Do you think right now that there are ‘unknown knowns’ – things we will know in future that we aren't even aware of today – and ‘known unknowns’ – things we will become aware of that we need to learn but still don’t yet know?
I'm smiling, because last night I was hosting [Cambridge University] astronomer royal Martin Rees and quantum came up – and literally that same phraseology was used. Quantum computing is not merely a new technology, but an Industrial Revolution for the first time since the end of the 19th century. Cars and computers were new technologies, but this is a revolution – it changes everything. Your children and mine will inherit, and be in a world which is so different: there will be things we don't even conceive of – never mind think of – that will change.
A quantum computer will be something – if we're lucky – that allows us to lift the veil on the nature of reality. And nothing could be more important than that, in my opinion.
The way you say that puts me in mind of someone I know who worked for a while with Stephen Hawking – she said she heard him say that within a hundred years science will disprove the existence of God. Was Hawking referring to quantum when he said that?
I was the chairman of the Stephen Hawking Foundation. I knew Stephen as well as it would have been possible to know him – particularly in the last five years of his life. He was a dear friend. He had a mind the size of a bloody planet! I think when we talk about people like Stephen – how many people have been alive, ever? Ten billion, 12, something like that? Of those, how many truly matter?
Maybe you could categorize them. If you're religious, you could say Mohammed or Jesus or the Buddha. You might be an artist, and decide Michelangelo or Velasquez or whatever. Or you might be into writing: Dante, Shakespeare, Homer perhaps. Now in science, the discovery of things, how many are there that really matter? Pythagoras possibly, Newton, Einstein, Galileo – there are not that many that really shift things. Stephen was one of them.
Whether it's God or the ultimate creator, whatever way you describe him, I think Stephen's right: I think quantum mechanics is really the nature, the laws of reality – because it's unchanging across the universe. You go to the depths of a black hole, or you could be going back 15 billion years to the birth of the universe, or at least as far as we're aware: quantum mechanics is unchanging. A quantum computer therefore – because it is a device that utilizes the rules of quantum mechanics – is a glimpse into the nature of reality.
Tell us more about this mechanistic underpinning of quantum computers – because classical computers being digital, this seems like another contradiction.
A quantum computer is a mechanical thing that generates a qubit. A classical computer is contrived – there's no reality in it, it's a junction or gate or transistor that's on or off. The information is the multitude of these on/off switches that then can represent a one or a two, or this live stream, but there's no physicality – the superstructure of this thing here [holds up cellphone] or even a supercomputer, is just a housing of many of these junctions. Information in a classical computer is just the memory of whether those things were on or off. In a quantum computer, information is represented by a physical thing. Now that takes a lot of getting used to – it's not intuitive.
You say a classical computer has no physicality, even though the device the information is stored in is physical?
It is ultimately physical like a photograph is physical. That's a memory – it's that instant in time captured. But when people talk to you about quantum computers they'll often say: “It's not digital, it's analogue” and that's what they mean. When [mathematician and cryptographer] Alan Turing came up with the idea of a computer, he wasn't thinking of a machine, he was actually thinking of an individual writing things down. And he was using first-order logic – the logic that [says]: “if this, then that.”
“If”, “and”, “or” – these junctions that we create intellectually, they're not real: they're in our minds. He used the rules of logic to create this way of computing, then of course that was mechanized, and we discovered that computers can do probably only one thing better than you or I – add up and take away. Because they can do that faster, they can multiply and divide – and because they can do that, they can do all these things.
Hence they compute...
That's right – they don't do anything else better than human beings. It's like an aeroplane does one thing better: it gets up, using thrust and loads of different kinds of mechanics. Now quantum computers embed information, or carry it I should say, in a physical thing. That thing is called a qubit. When you look at a quantum computer, it is a way of generating that thing – for now let's call it a photon. And then it enables that thing to be manipulated, like I'm manipulating this Blu Tac. And then it measures the result – just as in this [mobile calculator] when I put 2+2 and I hit “equals” it does a measurement and tells me what the result is.
There are many people with many different ideas about how that qubit could be generated and what that qubit should be. This is where it does get religious: there are people who will swear blind to you that their way of doing it is the best. Some people use optical or photonic quantum computers – using the unit of light – other people do superconducting quantum computing. Lots of people will tell you: “That one over there, don't trust him, mine's better.” We're still at that stage.
Is there any objective way to say which, if any, method of generating qubits is better?
My personal view is that we are a number of years away from knowing which of these methodologies is better. I would go one step further and say the likelihood is that some quantum computers will be better at one thing and some at another.
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