STFC-RAL-CR03 R61: Welcome, good morning, everyone. Welcome to this, PPD and QCC joint seminar. Title is Factor Split and Quantum Quicks.
STFC-RAL-CR03 R61: Our speaker. Welcome, David, and thank you for being such a sport yesterday through all of our adventures. If you want to know about it, I would be happy to tell it at lunchtime. So, what our speaker, David, is a molecular astrophysicist with interest in explanatory biosignature.
STFC-RAL-CR03 R61: Molecules in extreme environments.
STFC-RAL-CR03 R61: quantum computing and machine learning. He is an award-winning senior lecturer in the molecular physics and psychochemistry at the University of Hull.
STFC-RAL-CR03 R61: And teaches advanced quantum mechanics.
STFC-RAL-CR03 R61: Astrochemistry, data science, and scientific computing.
STFC-RAL-CR03 R61: He holds a biochemistry degree, from, University of Bizanne.
STFC-RAL-CR03 R61: a PhD in theoretical chemistry from UCL, and a German habilitation in theoretical chemistry.
STFC-RAL-CR03 R61: And David has authored over 70 peer-reviewed publications and has 25-plus experience… 25-plus years of experience in developing high-performance computing solutions.
STFC-RAL-CR03 R61: For problems in quantum chemistry.
STFC-RAL-CR03 R61: Molecular Physics and astrochemistry.
STFC-RAL-CR03 R61: He is an associate editor of Frontiers in astronomy and Space Science,
STFC-RAL-CR03 R61: Mainly it's a strong chemistry division.
STFC-RAL-CR03 R61: the principal UK investigator for the EU ETMOS project, and a collaboration partner for the KM3Net Neutronics program.
STFC-RAL-CR03 R61: He has many other accolades in his,
STFC-RAL-CR03 R61: In CB, but I will just skip them for now, and let's get to the seminar. Thank you, David, and welcome, the speaker.
STFC-RAL-CR03 R61: Thank you, thank you very much. I guess that was a firelander? Yes. So, we do. Okay, well, thank you very much for inviting me here today.
STFC-RAL-CR03 R61: It was a Louvrenderful statement, it's okay. So, I think…
STFC-RAL-CR03 R61: despite, I think, all, all the base interests, that you mentioned, also have,
STFC-RAL-CR03 R61: Quite a lot of interest in neutrino.
STFC-RAL-CR03 R61: physics, and I think this is probably also why it feels like it's a good, good idea to come in.
STFC-RAL-CR03 R61: book, do you guys do any? So, because…
STFC-RAL-CR03 R61: This talk will touch on lots of physics, particle physics, quantum computing, I thought I'd have a bit of a recap of
STFC-RAL-CR03 R61: everything as I go along. Any astrophysicists in the audience?
STFC-RAL-CR03 R61: Oh, there you go, there you go. One or two. I think usually, usually it's… this is a completely different thing. Usually, I have to explain a lot of, a lot of the particle physics in the quantum computing, because everyone knows the astronomy. So,
STFC-RAL-CR03 R61: I've pulled a couple of things from our, astrophysics sectors, just to explain to you what that kind of image is, and why we're interested in looking at,
STFC-RAL-CR03 R61: Retrios, particularly in the sort of…
STFC-RAL-CR03 R61: sort of dense neutrino regime. So.
STFC-RAL-CR03 R61: It started, I think, a while ago when we started looking at, explosion of massive stars. So, what happens… this is what eventually leads to what we call a supernova, which are one of these
STFC-RAL-CR03 R61: Great fireworks that you see, in…
STFC-RAL-CR03 R61: Well, I suppose we've gotten up quite a few pictures, and we can see signs of lots of
STFC-RAL-CR03 R61: these sort of events, particularly if you're from the neutrino community, we like those events, because they will usually generate lots and lots and lots of neutrinos. So.
STFC-RAL-CR03 R61: This usually works like this, where the star eventually runs out of fuel, so you have to take a reasonably big star, something that's about 8 times the mass of our sun, and it runs through all of the processes that it has that's making us use of
STFC-RAL-CR03 R61: Listen.
STFC-RAL-CR03 R61: nuclei's… One, it gets to iron. Iron is essentially
STFC-RAL-CR03 R61: The stable stop point at which the star can really extract much more energy out of fusion, so
STFC-RAL-CR03 R61: The call stops. Essentially, the fusion stops.
STFC-RAL-CR03 R61: And because that was balancing the gravitational pressure, new course starts to be sure to contract.
STFC-RAL-CR03 R61: Usually, stars do that all the time, right? So when that happens, usually it's fine, because that then reignites the fusion, and then it continues again. That's when we make the shells. But here, because we are iron, it just constructs… contracts and just goes, ugh, I can't really do very much.
STFC-RAL-CR03 R61: while that's happening, the last part of silicon burden continues depositing iron into the core until we reach a critical mass, and at that stage, it starts decides that it has enough particular the core, and I'm just gonna collapse. So it collapses, cools down.
STFC-RAL-CR03 R61: And generates… this is quite quick. This happens within about a second. The staff starts to collapse, the court collapses.
STFC-RAL-CR03 R61: And we have processes like neutralisations, photos and integration that starts releasing all sorts of nutrients.
STFC-RAL-CR03 R61: At one stage, Can you imagine this week's core collapsing?
STFC-RAL-CR03 R61: Things get smaller and smaller and smaller, and of course, at one stage, the nuclear forces just go, well, hang on.
STFC-RAL-CR03 R61: I mean, we're nice, but we're not that nice. At one stage, we're going to stop compressing this, so the nuclear force then essentially, of course, is forcing the core to rebound, and essentially a shock wave that is then sent back out, which is what is
STFC-RAL-CR03 R61: Fleet shown here on the… On the right, that causes the rebound, or called rebound shock.
STFC-RAL-CR03 R61: We don't think that is then the explosion of our supernova, but what happens is this shock then encounters the rest of the matter that keeps falling into the core, because gravitation keeps pulling things out. So, eventually.
STFC-RAL-CR03 R61: and the truck propagates outwards, I think that's what we have.
STFC-RAL-CR03 R61: on this nice diagram from Janka here,
STFC-RAL-CR03 R61: The shock sort of propagates forward, and then stuff keeps
STFC-RAL-CR03 R61: Coming down, which means that, essentially, with… I… stalled shock, so…
STFC-RAL-CR03 R61: shop front, and they fully might end up in some sort of
STFC-RAL-CR03 R61: With equilibrium for not very long, The call continues to become
STFC-RAL-CR03 R61: Trying to become a literal star, essentially. And then, you have, sort of, two options.
STFC-RAL-CR03 R61: If you can put more energy into that shock.
STFC-RAL-CR03 R61: you will go supernova, and you will have an explosion. If you don't.
STFC-RAL-CR03 R61: Eventually, you become a super bloated neutron star. This is not whatso physicists really call it, but that's what I call it. And then that is what is going to become a black hole eventually, because you… you have also mass units of neutron stars.
STFC-RAL-CR03 R61: So you have essentially those two options.
STFC-RAL-CR03 R61: And for a while, people were wondering, well, how do we know which of the two options are we going to be? The weird thing is we're not seeing necessarily quite as many black holes as we'd expect to see, if that was really always the case. So we thought, well, most of the time, then, there must be… I mean, most of the time, we're talking
STFC-RAL-CR03 R61: Supernova, so it's not like we've got…
STFC-RAL-CR03 R61: millions and millions of players, but most of the time, we see what we call a shockery viable.
STFC-RAL-CR03 R61: And so, this is what we treated with become interesting.
STFC-RAL-CR03 R61: People then thought that,
STFC-RAL-CR03 R61: Well, we still think that this occurs through what we call a delayed neutrino heating mechanism.
STFC-RAL-CR03 R61: So… What is that?
STFC-RAL-CR03 R61: The idea is… your…
STFC-RAL-CR03 R61: neutron star has to cool down, and essentially because there's a lot of energy from gravitation when you're actually making a neutron star. So.
STFC-RAL-CR03 R61: The neutrino is probably the best way of getting energy out of there.
STFC-RAL-CR03 R61: And the neutrinos then interact with, the free neutrons and protons that are there, so we have, some capture that occurs, heat up this, what we call this gain layer.
STFC-RAL-CR03 R61: quite close to the core of the star, and the thinking is that this reheated gas eventually, is able to come in the shock, revive the shock, and essentially build supernova. So.
STFC-RAL-CR03 R61: From an astrophysics point of view, sleep bye then.
STFC-RAL-CR03 R61: my astrophysicist colleagues are happy, they're like, yeah, yeah, that's fine, and then I start talking to them about neutrinos. They fall asleep, because they're like, well.
STFC-RAL-CR03 R61: whatever, you know, we know how it works. I'm like, well, actually, maybe we don't really know how this works, right? This is quite a dense… so, this is the thing, usually.
STFC-RAL-CR03 R61: This is an extremely dense region, and we can imagine having strongly interacting neutrinos, so actually trying to understand what's happening in that strong interaction region is important for
STFC-RAL-CR03 R61: One, all trying to understand fully the heating, but there's also other aspects of
STFC-RAL-CR03 R61: The dynamics of what's happening in the explosions, whether similar explosions, if you don't include neutrinos or anything, you have usually some issues.
STFC-RAL-CR03 R61: And it has also, ultimately, some implication on nuclear synthesis, and what sort of elements are produced when,
STFC-RAL-CR03 R61: When stuff comes out of the supernote.
STFC-RAL-CR03 R61: All right.
STFC-RAL-CR03 R61: I will stop talking about astrophysics for a bit. Now, clearly, I had some slides on particle physics.
STFC-RAL-CR03 R61: I'm gonna go through quite quickly, because I'm hoping most of you will not necessarily need to,
STFC-RAL-CR03 R61: tell you what neutrinos are, but all the same, you know, I have one of my PhD students kindly prepare some neutrino slides, and it feels like I have to show them, because
STFC-RAL-CR03 R61: They're quite nicely made, but we have some nice, nice, pictorial description of neutrinos. So, for people who don't know, neutrinos are in energy particles with remote charge, and a very small mass.
STFC-RAL-CR03 R61: A very, very small mask. And, the… Exists in two distinct flavors.
STFC-RAL-CR03 R61: So, the catch with neutrinos is that
STFC-RAL-CR03 R61: We have detected those through their interaction with particles. We have not. So we name them after the interaction they came from. So we have electron neutrinos, neon neutrinos, and tau neutrinos.
STFC-RAL-CR03 R61: But… these… Naming of neutrinos do not coincide with their mass eigenstones, which means that, in general.
STFC-RAL-CR03 R61: we can't really say, oh, a nurturing neutrino has that much mass. It's a mixture of mass states, which,
STFC-RAL-CR03 R61: is… Quite.
STFC-RAL-CR03 R61: complex, I suppose. It's not super complex. We see there's three. The…
STFC-RAL-CR03 R61: whether M1 is smaller than M2, which is smaller than M3, or whether it's the other way around, is not completely settled, although we tend to prefer M1 smaller than M2 smaller than M3. And…
STFC-RAL-CR03 R61: Then the famous thing that we observe, so the thing that the interaction is happening with, is a superposition of mass eigenstates. This is essentially
STFC-RAL-CR03 R61: I think for someone who's a quantum mechanics person, I'm just fine with this. I'm like, sure, just have a superposition of these states, and there's a unitary matrix that connects all of these. It's called the Q&S matrix, and
STFC-RAL-CR03 R61: Everyone's busy measuring some of the elements of that matrix, but…
STFC-RAL-CR03 R61: Overall, like, okay, so it's every particle is sort of a mixture of these three mass states.
STFC-RAL-CR03 R61: That's the part I don't usually show to the astrophysicists, because
STFC-RAL-CR03 R61: you remember by now the IC. The thing that wakes them up a little bit is this, because I say, well, okay, so why don't care?
STFC-RAL-CR03 R61: Well, what actually matters is that
STFC-RAL-CR03 R61: Imagine you produce a neutrino in specific flavors. Okay, for example, say it would take an electric neutrino, because this is actually what happens.
STFC-RAL-CR03 R61: The astrophysicists know very well, called the solar eclrion, which is… you can actually calculate how many
STFC-RAL-CR03 R61: electric neutrinos are being produced by, for example, old sun, and then when that got measured, suddenly there was a bit… we didn't get quite as many as we expected. And this is because
STFC-RAL-CR03 R61: Since they don't have a definite mass, it's just a superposition of three mass states. As you travel, or as they travel through space.
STFC-RAL-CR03 R61: they will oscillate, so the electric neutrino that we produce, and if you measure it later, for example, here at Earth, will be… could be detected as a muon or a tongue neutrino.
STFC-RAL-CR03 R61: And the initial case could not be detected at all, because they have
STFC-RAL-CR03 R61: I think in the original expense, there were only
STFC-RAL-CR03 R61: detecting electric neutrinos, and… because they… they…
STFC-RAL-CR03 R61: will be… well, they are the only ones that actually interact reasonably with matter. So.
STFC-RAL-CR03 R61: That got people, usually, astrophysicists, are a little bit more interested in matrinos. I'm not saying they're not interested, it's just that they have other stuff that they're particularly interested in.
STFC-RAL-CR03 R61: So,
STFC-RAL-CR03 R61: We want to simulate this, we want to understand neutrinos just a bit more, so we can do things like,
STFC-RAL-CR03 R61: Oscillations, so these are… this is some of the
STFC-RAL-CR03 R61: Early examples of what we did a little while back on using quantum computers to simulate neutrino simulations.
STFC-RAL-CR03 R61: I will talk to you a little bit more about this, but I just wanted to show you that this is typically a sort of oscillation profile that we have. We are all, you know, weird neutrino units of length divided by energy.
STFC-RAL-CR03 R61: Because most of your part of this is true. You'll be all down with that, this is fine. And here, this is looking at what we call the survival probability, so this is the probability of,
STFC-RAL-CR03 R61: the… essentially, the neutrino is still staying what it… staying as it is, so if we start initially with an electric neutrino, it also changes flavor and then comes back up, again, as an electric neutrino a little bit later on.
STFC-RAL-CR03 R61: And then we have similar profiles for
STFC-RAL-CR03 R61: neons and tauves. What excited us reasonably well at the time is the dots that we see is what was simulated using, one of the, quantum computers that the NQCC put at our disposal, and
STFC-RAL-CR03 R61: we're like, okay, this is, this is fine, this is roughly okay. We, we broadly reproduce what happens, and it seems to follow
STFC-RAL-CR03 R61: theory reasonably well.
STFC-RAL-CR03 R61: So then we thought, let's be bold. This is just a neutrino in vacuum, a single neutrino in vacuum. Maybe we can do better than this. So then we went through to adding some matter oxidate, so matter potential, so this was
STFC-RAL-CR03 R61: what we call a Wolfenstein potential, which essentially simulates how Electron neutrinos interact with matter.
STFC-RAL-CR03 R61: It doesn't have interactions for the real model channel, and what we'll see
STFC-RAL-CR03 R61: is, sort of what we'd expect. We have the top panelists, the Electron
STFC-RAL-CR03 R61: channel, so we're looking at a single mule neutrino that is now left to its own device, and propagate there. And as we increase the strength of
STFC-RAL-CR03 R61: The matter interaction, we see that our survival probability just goes down and down and down, while the,
STFC-RAL-CR03 R61: where the other channels, Neon and TAF, are getting a little bit… increased,
STFC-RAL-CR03 R61: we're happy with this. I mean, this sort of works reasonably well. This was also a test of the quantum computing simulations, and they… they are pretty much close to what we'd expect for the analytical results. Now.
STFC-RAL-CR03 R61: Clearly.
STFC-RAL-CR03 R61: This is just a single neutrina. We have analytical solutions for this, we don't need to be a multi-computer for that.
STFC-RAL-CR03 R61: So, why do we do this? Well, the idea is, first, we wanted to test, whether it actually,
STFC-RAL-CR03 R61: of where it actually works, because this is meant to be a reasonable problem to run on a quantum computer. But what we wanted to do, ultimately, is try and see whether, if we start adding more and more.
STFC-RAL-CR03 R61: neutrinos, maybe this gives us a simpler formalism to actually
STFC-RAL-CR03 R61: look at interactions at… or quantum interaction at the larger scale. Remember, what we want to do is try and understand what happens when we have loads and loads of neutrinos, ideally near a star, or inside an exploding star, and try and understand what's going to
STFC-RAL-CR03 R61: So we started looking at introductions, so…
STFC-RAL-CR03 R61: Traditionally, neutrinos don't really interact very much with each other. It's a bit like, sometimes when I talk to people who do photonic quantum computers, I think it's a bit, and sometimes, you know, when you try and entangle them, it's a bit harder, but,
STFC-RAL-CR03 R61: The idea is here, because we're in a dense medium inside a coarse collapse supernova, we think there's definitely a good,
STFC-RAL-CR03 R61: good chance that they will likely interact, because they are all quite tightly close to each other. From a particle physics point of view, we'll parameterize those, using some sort of forward sketching process, which is what we call refraction processes.
STFC-RAL-CR03 R61: Where you have, Essentially, Things are either, leave your
STFC-RAL-CR03 R61: Your neutrinos, stuff, and change with… with respect to that.
STFC-RAL-CR03 R61: We're ensuring the final momenta, or you have a sort of exchange scattering normally, exchange momentum from particles.
STFC-RAL-CR03 R61: And it's so reasonably well documented.
STFC-RAL-CR03 R61: This is a paper from 95 or so, but there's plenty of literature on people looking at how we can look at neutrino-neutrino interactions. In our case, we're interested both in the neutrino and anti-neutrino sectors, so we're going to part all of those together.
STFC-RAL-CR03 R61: But we still wanted to put all of that on a quantum computer, because we thought, hmm, yeah, maybe…
STFC-RAL-CR03 R61: a very, very large collective regime, might be an interesting, case study for Xi.
STFC-RAL-CR03 R61: So… What we did is use… use what we call a simplified collecting tumor model.
STFC-RAL-CR03 R61: We decided, even though there are 3 flavors, we only use 2 to make things easier. To be honest.
STFC-RAL-CR03 R61: Most of the interesting things happens.
STFC-RAL-CR03 R61: The electron neutrinals, because they're the ones that interact the most with matter, so
STFC-RAL-CR03 R61: will, keep those. In particular, also, they're the ones that seem to participate more, readily in all of them.
STFC-RAL-CR03 R61: Reactions that we've seen.
STFC-RAL-CR03 R61: And then we'll just have, like, electrone neutrino and other.
STFC-RAL-CR03 R61: You're shooting out X.
STFC-RAL-CR03 R61: And we'll be okay. So it's a… it's a two-state model, which would make the math this a bit simpler. And then, in that case, if we do it this way, we have two mass,
STFC-RAL-CR03 R61: mass channels, that we call mass 1 and mass 2, and we use what we call the vacuum mixing angle, which will correspond to, I think this is electron mixing angle. It's an approximation, but the idea is we want to go for
STFC-RAL-CR03 R61: For a large collection of neutrinos, and we can always make it harder afterwards.
STFC-RAL-CR03 R61: We're also going to change a little bit, and we're going to ignore initially the,
STFC-RAL-CR03 R61: matter interaction. We put it back up towards lithium, but initially we thought we'll just have a standard vacuum propagation, and then what we're interested in is adding this interaction between the treatments.
STFC-RAL-CR03 R61: So… There's actually quite a convenient way of writing this using Whoa.
STFC-RAL-CR03 R61: People call flavor isosphere notation.
STFC-RAL-CR03 R61: Mainly, this becomes clearer later when we look at how this maps to a quantum computer, but it enables us to look at a set of spin operators, so we have one terms that looks after the vacuum oscillations.
STFC-RAL-CR03 R61: So we have a mass spectra, direction that looks at.
STFC-RAL-CR03 R61: The mass trajectories, and then we're looking at how the isospin is, parallel or perpendicular.
STFC-RAL-CR03 R61: conduct a mass direction.
STFC-RAL-CR03 R61: And then the slightly more interesting part when we talk about interactions is essentially how two neutrinos
STFC-RAL-CR03 R61: momentum, or isos, isosphere might couple to each other, and
STFC-RAL-CR03 R61: Here we have a coupling constant.
STFC-RAL-CR03 R61: and a sort of cosine-dependent strength, which will sort of help us tell whether your neutrinos are sort of collinear, or whether they are deviating a little bit. We'll see when we,
STFC-RAL-CR03 R61: And I streamline the model in about a minute, that the assumption is that the neutrinos will sort of radiate out, so that they sort of come out with a slightly different angle. I've got them here.
STFC-RAL-CR03 R61: So,
STFC-RAL-CR03 R61: If we imagine the core of our star here, and, so there's what we call the neutrino sphere, which is… which sort of starts a little bit before the… or finishes a little bit before this, almost look up from 60 kilometers from the center to about 250 kilometers.
STFC-RAL-CR03 R61: And the idea is the neutrinos would stream out like this, and they… they can, you don't have to, but they can have, like, a slight different, slightly different solid angle between them, so we've had
STFC-RAL-CR03 R61: To the neutrinos, and, And we'll write it like that. Now.
STFC-RAL-CR03 R61: If we look at what the Hamilton looks like, And… We… I don't…
STFC-RAL-CR03 R61: built on, I suppose, a… a hat of,
STFC-RAL-CR03 R61: say, condensed matter physicists for a minute. This actually looks like
STFC-RAL-CR03 R61: sort of an async time model, or a Heisenberg-type model. It looks like a model where we would have a set of magnetic spins, so if I was to write
STFC-RAL-CR03 R61: magnetic Hamiltonians, It would look very much like a state, the
STFC-RAL-CR03 R61: constant, or the strength is slightly different, but that's roughly what it looks like, which
STFC-RAL-CR03 R61: is actually going to be quite good news for us, because the quantum computing people spend quite a lot of time solving, magnetic phase transition, this kind of thing, so a lot of the tools are already there.
STFC-RAL-CR03 R61: We're going to assume that the coupling strength isotropic for us, that we don't have any problems.
STFC-RAL-CR03 R61: The neutrinos now are emitted, and essentially they will… they will travel quite far and fast, and they will drift apart, so we'll simulate this by changing the coupling strength, because we… they're going further and further away.
STFC-RAL-CR03 R61: We're interested in having a model where we can look at, essentially, some gravity influence from there. We're quite close to quite a massive object. It might even be from a black hole at some stage. What are the effects on some of the, some of the parameters?
STFC-RAL-CR03 R61: And clearly, there's many, many ways of doing it. So people have been doing this for a while. You have, two sort of types of approximations that people are doing. There's what we call a single angle approximation, where you have two, like, all the
STFC-RAL-CR03 R61: All your neutrinos, coming up whole linearly, senior competing.
STFC-RAL-CR03 R61: And then you have something that looks a bit like a… I suppose in… in…
STFC-RAL-CR03 R61: The electronic structure, we call it a random phase approximation, to some extent, where you sort of more or less trying to
STFC-RAL-CR03 R61: Write out your, your expectation values of, of your,
STFC-RAL-CR03 R61: dot product as a product of the expectation value, so essentially trying to trace out a set of degrees of freedom, and you have an effective potential. This is sort of a mean field engineering of sorts.
STFC-RAL-CR03 R61: They both work, but I think the question that we're trying to pursue is to say, well, sure, they might work, but what are we neglecting? What effects are maybe not there when we look at the mean field rather than instantaneous interactions?
STFC-RAL-CR03 R61: All right.
STFC-RAL-CR03 R61: Only a quantum computing experience.
STFC-RAL-CR03 R61: Not many. Okay, that's good, that's good.
STFC-RAL-CR03 R61: So I have a couple of slides to explain,
STFC-RAL-CR03 R61: quantum computing. So, the idea? Yeah.
STFC-RAL-CR03 R61: As you could very rightly ask yourself, walnuts…
STFC-RAL-CR03 R61: But we just have perfectly fine computers? We do! We have very good computers. I spent ages programming normal computers for probably most of my time. But, the idea here is
STFC-RAL-CR03 R61: Quantum computing could give us just slightly different pathways of doing things. The idea there is, if we can map our system, we essentially don't have to calculate it, we just have to observe it. So it's a bit like…
STFC-RAL-CR03 R61: Constructing an experiment that happens to solve the problem that we're looking at.
STFC-RAL-CR03 R61: So, how does that work? Instead of having
STFC-RAL-CR03 R61: Normal bits, like the rules 0 and 1, we have.
STFC-RAL-CR03 R61: two bits that have stage 0, state 1, and typically people represent this on this block sphere here, so the idea would be if you want state 0, you're at the top, if you're at stage 1 at the bottom, but because this is
STFC-RAL-CR03 R61: auto mechanics, The coefficients that you have can be complex numbers, and that also means that you can make
STFC-RAL-CR03 R61: essentially combinations of zeros and ones. So, if you want to simplify that to be extreme, it's like saying, instead of being just on and off, you could be anywhere between on and off on a complex way.
STFC-RAL-CR03 R61: We need, like we do on a normal computer, to be able to
STFC-RAL-CR03 R61: perform operations on this… on this quantum base. This is usually, done using unitary rotations. You can rotate these.
STFC-RAL-CR03 R61: And these end up being, SU cube body matrices, so we can make superpositions. There's also a whole set of,
STFC-RAL-CR03 R61: Of operations that enable us to look at multiple qubits, so essentially how we go from
STFC-RAL-CR03 R61: a 1, 2, 3, 4, 5, at the minute. Some of the You need to get…
STFC-RAL-CR03 R61: Probably up to, reasonably, 200 and, also on atom-based,
STFC-RAL-CR03 R61: Onto the computer. The ones we've been using are around 100, 120.
STFC-RAL-CR03 R61: qubits, so we have also gates that enable us to, to control what happens, and this, lets us make non-classical states, or entangled states.
STFC-RAL-CR03 R61: This is where we have, essentially, where we say, oh, if this qubit does this, you do that with the other one tech.
STFC-RAL-CR03 R61: So we can generate an algorithm with those, very much the same as we can generate an algorithm on a normal.
STFC-RAL-CR03 R61: a classical computer. Of course, it sort of… when you're doing it that way, it brings us back to…
STFC-RAL-CR03 R61: a bit more like the very early days of computing, where really you end up having to, you know, you specify your circuit, and it does things that way. It's sometimes really close to, sort of, how you might do it with, sort of, actual electronics.
STFC-RAL-CR03 R61: But, despite of all this great
STFC-RAL-CR03 R61: quantum things that you can do on these quantum operations. Ultimately.
STFC-RAL-CR03 R61: You still have to get the results… you still have to get some classical results out, because the normal computer value interface is not classical, so you measure your qubit, and in the end, you just get 0 or 1.
STFC-RAL-CR03 R61: And… the only advantage or disadvantage, I mean, the advantage is you can sort of
STFC-RAL-CR03 R61: Tailor what sort of results you're going to get, because it comes with a, it comes out with a probability that's proportional to the coefficients that you've put in.
STFC-RAL-CR03 R61: But that's also the disadvantage, because you don't really get a different answer, you just get a probabilistic answer to what the result is. So usually, typically, we will run these experiments many times.
STFC-RAL-CR03 R61: And this is a simple experiment that I've worked out for you. These are real results from one of the machines, where I was, I think, trying to get it to measure, sort of, mixed
STFC-RAL-CR03 R61: entangled state. I was… I'm not a particularly lucky person in general, as well, so I was expecting a sort of 50-50 thing. It didn't quite work out that way, so it would…
STFC-RAL-CR03 R61: we've got, sort of, this one is 0, 1, and 1, 0, so you end up with something. I always see that when we do measurements for capsule.
STFC-RAL-CR03 R61: Some little fringes here. But, you know, by and large, you could sort of work out that, okay, it's doing things, it's got qubits, you can make things, and it sort of does what you want.
STFC-RAL-CR03 R61: Right? So I was like, oh, this is good.
STFC-RAL-CR03 R61: Let's map. So…
STFC-RAL-CR03 R61: we only have two states. That works quite well, so we can map our flavors, we can say, okay, electron.
STFC-RAL-CR03 R61: Neutrino is going to be zero, state zero,
STFC-RAL-CR03 R61: Although, neutrino will be state 1.
STFC-RAL-CR03 R61: The ISO Spins operator
STFC-RAL-CR03 R61: also align with SC2-type algebra, so I was like, oh, this is like a polymatrix, so we can use polymatrices now to act as our isospin operators.
STFC-RAL-CR03 R61: And because we have an isotropic interaction, this is actually what we call an XXX Heisenberg model, where everything is isotropic in all directions.
STFC-RAL-CR03 R61: So we can essentially rewrite or equation in terms of
STFC-RAL-CR03 R61: a poly matrix here, and some X matrices. And here, there's a couple of, sorry, X, Y, and Z polymatrices, so that… this part implements the Heisenberg model, and this is doing the vacuum.
STFC-RAL-CR03 R61: There's a couple of factors that creep up just because of the way these particular polymatrix are implemented on the quantum computer.
STFC-RAL-CR03 R61: But, basically, all we need to do then, we set up the figures that we want, We'll say.
STFC-RAL-CR03 R61: quantum computer, he's a Hamiltonian.
STFC-RAL-CR03 R61: please do the thing properly. And so we can evolve, then, the state from, sort of, the end of the neutrinosphere
STFC-RAL-CR03 R61: Inside the game like an apostle creature.
STFC-RAL-CR03 R61: So, in practical terms, this is my…
STFC-RAL-CR03 R61: Last slide on, on, on team computing, so we… This is theory, this is…
STFC-RAL-CR03 R61: Essentially, what we do, we have states, we have… we apply Hamiltonian.
STFC-RAL-CR03 R61: We have to essentially discretize this, to make it,
STFC-RAL-CR03 R61: computable, because most of those, there's rotation relations, etc, so we end up having to make extra small steps. So we ended up sort of splitting things into half steps.
STFC-RAL-CR03 R61: It turned out that instead of using time, it was probably easier to use radial steps, but that's sort of the same thing.
STFC-RAL-CR03 R61: I think the interesting thing is we end up with, essentially, a circuit, which is how we
STFC-RAL-CR03 R61: programmed onto the computer. That is reasonably simple in the sense that we have
STFC-RAL-CR03 R61: Flavor to mass at the start, transformation and mass to flavor transformation at the end, and then in the middle, we will just, do path back, or interaction, path back, and that…
STFC-RAL-CR03 R61: yellowish bit is what moves the wave function forward. So we do… if you're on the first time step, you just do it once. If you're on the second time step, you do it twice, and then et cetera, et cetera. So you sort of repeat this as many times as you want, and by the end, you have repeated it
STFC-RAL-CR03 R61: 40 times, 50 times, whatever many times you want, and you start then from the end, and it just carries you all the way.
STFC-RAL-CR03 R61: to the F.
STFC-RAL-CR03 R61: The aim was to do about 100 neutrinos or qubits model.
STFC-RAL-CR03 R61: I'll put that out there, because now I'm going to show you some results. We'll be able to reflect on whether that is a realistic goal in this particular building.
STFC-RAL-CR03 R61: So… Well, okay, let's… let's be exciting. Let's… let's start test things. So, we…
STFC-RAL-CR03 R61: starting with putting no interactions into things. This is the vacuum propagation, it should be the same sort of code that we have before. I'm starting with just two neutrinos, a neutrino and a neutrino, so I've got two sectors here, neutrino sector and neutrino sector.
STFC-RAL-CR03 R61: And…
STFC-RAL-CR03 R61: We're just looking at oscillations and how they are reproduced compared to the analytical. This looks really good, because this is a simulation of the quantit function. So, very, very long time ago, when I started doing this, people said, oh.
STFC-RAL-CR03 R61: Always start with simulation, because
STFC-RAL-CR03 R61: you, you know, you need a simulation. You need a simulation. So we need a simulation, so this works quite well.
STFC-RAL-CR03 R61: And we're like, okay, does it work when we…
STFC-RAL-CR03 R61: Add, some interactions. When we start to put the interaction, we see things are starting to get a little bit dampened, and it's, we see there's a bit of structure there, but…
STFC-RAL-CR03 R61: It seems to work, it's okay. We use adaptive steps, because the idea is we have stronger oscillations at the start, we have at the end, so we don't need maybe as many 5 steps towards the end. This is working well.
STFC-RAL-CR03 R61: We then also started looking at simulating, sort of, a 3 plus 3 system, so here we have, we have…
STFC-RAL-CR03 R61: A set of three different energies for initial neutrinos, and what we start seeing
STFC-RAL-CR03 R61: I wanted to compare this with the, single angle approximation to nuclear approximation of infields of split things, so low electric energy.
STFC-RAL-CR03 R61: keep their flavor. High-age neutrinos tend to
STFC-RAL-CR03 R61: lose their flavors. We have a sort of…
STFC-RAL-CR03 R61: There's separation given, and you see that the quantum part sort of follows it, roughly.
STFC-RAL-CR03 R61: And that seems to happen on both, on both sectors. Seems to be dampened quite a bit.
STFC-RAL-CR03 R61: But if we actually move to, a multiple angle model, so… which is close to what we're simulating in our…
STFC-RAL-CR03 R61: In our model, we've got a little bit less spitting, and
STFC-RAL-CR03 R61: Roughly, you know, if you scroll it.
STFC-RAL-CR03 R61: You go, yeah, yeah, okay, it sultan works.
STFC-RAL-CR03 R61: So, it's reasonable.
STFC-RAL-CR03 R61: And bolded by this, we thought, we'll now go on the real machine and see how whether we can actually reproduce the squiggles, whether it's squiggles.
STFC-RAL-CR03 R61: Oh, okay. So, here's a real machine, you'll start paying to pay some real money now. So, it's not my money, it's the NQCC's money, but all the same, you know, we're mindful. So, I'm going to do only 20 times, 20 steps.
STFC-RAL-CR03 R61: Because I know roughly what's happening, so I'm going to undersample some of the oscillations, so sometimes when there's things like that, because we know that underneath there's probably quite a few oscillations underneath, but I wanted to see, roughly… I'm interested to see whether I see that phase separation. I'm not going to have phase separation with a 1 plus 1 system.
STFC-RAL-CR03 R61: But this was the serination at the top, right? This is the real machine at the bottom, and I was like, oh my goodness, mate, this is really good, this is close, this is really close! Oh!
STFC-RAL-CR03 R61: So good. I felt really happy.
STFC-RAL-CR03 R61: No, no.
STFC-RAL-CR03 R61: added more neutrinos, so I have my simulation at the top, and then I'm like, oh…
STFC-RAL-CR03 R61: what is happening here. This is the real calculation, so I started to be a bit too…
STFC-RAL-CR03 R61: Okay, not quite what I expected, but alright.
STFC-RAL-CR03 R61: Maybe it's just too frustrating.
STFC-RAL-CR03 R61: Who knows?
STFC-RAL-CR03 R61: Just a few more.
STFC-RAL-CR03 R61: Things in there. Simulation, fantastic. Read machine, blah.
STFC-RAL-CR03 R61: Yeah. I mean, you know, if I'm being…
STFC-RAL-CR03 R61: you know, super optimistic. Not the right ones, but it's also followed some of the curve.
STFC-RAL-CR03 R61: So…
STFC-RAL-CR03 R61: what sort of is going on? This was my… my thinking was taking the bus to come here, depending on which side was that. The simulation worked really well. It was really good. It looked super promising. And now I've run it on a real machine.
STFC-RAL-CR03 R61: And it's a little bit bleaker than Whittle. I mean.
STFC-RAL-CR03 R61: We know this, to some extent, right? It's like, whenever you do something experimentally, you have some measurement errors, etc, etc. I think here there's a couple of things that happen, the simulation.
STFC-RAL-CR03 R61: Are not really taking much
STFC-RAL-CR03 R61: much of the actual video here, so simulations are a bit too, ideal, if you wish. Yep. You're using this QScript for simulation? Yes, yes, yes. There you are also loading the…
STFC-RAL-CR03 R61: there's something called machine dynamics, something like that. Yeah, so you can, you can load, you could take into account the parameters from the machine, etc, to try and make the simulation even more realistic. But, ultimately.
STFC-RAL-CR03 R61: the way this works is when I make all these many, many steps, I probably hit what we call,
STFC-RAL-CR03 R61: some of the issues with, essentially, the survival of these qubits. So they sort of eco here, and by the time, in fact, most of the curve ended up roughly around halfway, which is what you'd expect if you put things that were a little bit done.
STFC-RAL-CR03 R61: You know, we don't… I'm not panicking quite yet, because…
STFC-RAL-CR03 R61: The two-level model actually fits quite well for quantum computer.
STFC-RAL-CR03 R61: In simulations, they both
STFC-RAL-CR03 R61: Show, sort of, this onset of face transition, like this splitting that we may be looking for, just because it's interesting, and it's more of a mark of, sort of, these,
STFC-RAL-CR03 R61: We sort of condensed… system.
STFC-RAL-CR03 R61: running on… or running on Vienna hardware, actually is really not what we need in order to be able to develop better versions of this. So, now, the plan is
STFC-RAL-CR03 R61: We know how to fix this, but we're only about one month into this project, so…
STFC-RAL-CR03 R61: there's a bit of time left. I have a very good idea of how to fix this, but I wanted to first, you know, first you start simple, and you go, okay, how…
STFC-RAL-CR03 R61: How well, you know, will… will this work? And…
STFC-RAL-CR03 R61: It's interesting that even though hardware has come on quite a bit, you can't just
STFC-RAL-CR03 R61: You know, you have to still be quite careful into how you program these computers.
STFC-RAL-CR03 R61: I've sort of popped them just on time, and I'll finish with this.
STFC-RAL-CR03 R61: Also, a huge thank you to NQCC.
STFC-RAL-CR03 R61: that have been very patient with us and gave us lots of computing time, and, or HPC at home as well, and…
STFC-RAL-CR03 R61: Thank you.
STFC-RAL-CR03 R61: I think I have about 100 questions. Okay. Let everybody run fast first, so please…
STFC-RAL-CR03 R61: Can I go back to the beginning? It's probably implicit in everything you're talking about, but you didn't… you didn't mention the early exclusion principle, and that's what's stopping the star… That's right. Does it back pressure on the neutrinos? I think, so what happens is it's usually
STFC-RAL-CR03 R61: It stops the collapse, but then they get… you get to a point where they get sort of reabsorbed into this neutronization phase, where the electrons that usually would keep
STFC-RAL-CR03 R61: Keep the core from the collapses get reabsorbed into the nuclei, and they essentially lose the most powerful there, and then they continue to get there.
STFC-RAL-CR03 R61: But I was worried about the neutrino emission being held up, because foreign states… Oh, okay, yeah, so…
STFC-RAL-CR03 R61: What happens is, when you have quite a lot of
STFC-RAL-CR03 R61: quite a lot of electrons and masses, so yes, it does block some of the neutrino emission, because it's sort of quite opaque in the initial stages, but by the time you reach
STFC-RAL-CR03 R61: the, sort of, end phase, which is where you're making your neutron star, this becomes much less focused to neutrinos, so you suddenly have streams. These are the, sort of, neutrino streams that we can see, sort of, from outside. They come more for what we call the late stage.
STFC-RAL-CR03 R61: total neutron star type station, the ocean. You're right, at the early stages, when you have all these neutrino emissions, they… they…
STFC-RAL-CR03 R61: are a bit trucked in the show,
STFC-RAL-CR03 R61: regulators as well.
STFC-RAL-CR03 R61: Isn't it the case that, I mean, you've got inverse beta decay happening in the core, and what's happening is you're releasing neutrinos during the protonutron phase, and what happens is you've got some multiple scattering of those neutrinos. That's right. So they're not actually coming out at parallel. Exactly, but they're usually random. So if you look at the
STFC-RAL-CR03 R61: surface of the, say, neutrino sphere surface, they're coming out to all angles. Exactly, yeah. So your initial graph showed two neutrinos coming out.
STFC-RAL-CR03 R61: say, divergent. Yeah, it's… it's not actually correct. Well, it's… I think… I think what you can do is you can then play with, obviously, the angle that they're coming at us, which is what, you know, probably when we do these multi-angle, we will also…
STFC-RAL-CR03 R61: pick those up random. I mean, you're entirely right, there's… there's no real reason why we get, like, streams, like, there will… there will be,
STFC-RAL-CR03 R61: they will be scattered, and they'll come up different angles, yes. Yeah, totally, yeah. I think here was more…
STFC-RAL-CR03 R61: I thought I'd make…
STFC-RAL-CR03 R61: a picture that sort of shows the parameters rather than, necessarily. So, just another question. Were you actually considering,
STFC-RAL-CR03 R61: the region between the foot and the star surface, so the earlier surface, and the shock, and you're considering that just vacuum. Absolutely. That's actually quite important, so the…
STFC-RAL-CR03 R61: The matcha interaction is quite important. In fact, we can often show in this other simulations I've shown that if you actually include matching interaction, you could sometimes even quench the entire thing entirely.
STFC-RAL-CR03 R61: We've removed it initially because we wanted to see whether, if left… if we assume it's maturing, which it clearly isn't, do we, you know, what is the physics that we're seeing there? And then the plan is to then add material interactions back
STFC-RAL-CR03 R61: to try to see what, okay, does… or does that affect the dynamics that we're seeing? But yeah, definitely, I mean, you know, at the minute, this is not a realistic
STFC-RAL-CR03 R61: supernova simulation, because it's missing… the matter is missing, there's… it's not enough neutrinos to really be
STFC-RAL-CR03 R61: even competing with some of the mean field theories, but the idea was to try and construct this from the ground up, and then add the effects, one after the other, to see, okay, this does this, this part does that, etc, etc.
STFC-RAL-CR03 R61: So, would the end game, your simulations actually explain the explosion? Because we don't know how the star explodes. Yeah. Exactly. So I think the end game… well, if we could explain the explosions, fantastic. I think…
STFC-RAL-CR03 R61: We'll have to be probably a little bit more modest here and say, well, the end would be to already see if you have
STFC-RAL-CR03 R61: maybe…
STFC-RAL-CR03 R61: Quantum neutrinos, you know, neutrinos with a quantum description, and we're trying to see how can we go to see, can we maybe validate some of the midfield models, and then say, okay, they all seem to be alright, and then you could use the midfield models to describe
STFC-RAL-CR03 R61: the properties reasonably accurately.
STFC-RAL-CR03 R61: Or are we seeing some, sort of re-correlated effects that you're sort of missing out?
STFC-RAL-CR03 R61: from, mean field, because you could do multiple angle mean field models, right? People do that, this is fine. I think the question is.
STFC-RAL-CR03 R61: coming from something that is maybe more, like… I know, for example, in electronic structure theory.
STFC-RAL-CR03 R61: this is not correct, that the mean field model misses out lots of correlated things, and we usually have to add it back. So the idea was to say, well, if we take this to neutrinos.
STFC-RAL-CR03 R61: to neutrino physics, you will see a signal.
STFC-RAL-CR03 R61: how much are we missing by using a meat field compared to an explicit calculation? I think that was the motivation behind it. And it may be that that then would explain some of the weirdness that would have, but it's still part of the physics that we need to add before we can say, this is a
STFC-RAL-CR03 R61: But for a supernova type model.
STFC-RAL-CR03 R61: I agree.
STFC-RAL-CR03 R61: Sorry, I probably just didn't follow, but I didn't understand what advantage you were getting from the quantum community. You seem to be validating it all against classic law. Yeah, so there's only so much that you can do,
STFC-RAL-CR03 R61: There's only so much that you can do
STFC-RAL-CR03 R61: without the quantum computers. So, you can simulate this classically up to about…
STFC-RAL-CR03 R61: 30 cubits, so 30 particles in total.
STFC-RAL-CR03 R61: When you get to 35, 36, you need supercomputers. By the time you get
STFC-RAL-CR03 R61: to 40, basically, I would probably have to use the whole of Iraq.
STFC-RAL-CR03 R61: And I probably wouldn't even get that. So, you hit a limit on sort of your explicit calculations. So, the only alternative that you have is that you have to do mean refills.
STFC-RAL-CR03 R61: So, our hope is that Once you get on a quantum computer, the quantum computer will happily give you
STFC-RAL-CR03 R61: 100 qubits, and give you the result for that. The classic, you know, you will have to measure it, so you get the result, but you can, within the quantum computer, run the
STFC-RAL-CR03 R61: want to, you know, have no wind field at all. You can have the total exact import result.
STFC-RAL-CR03 R61: And I think…
STFC-RAL-CR03 R61: What we're up against at the minute is making sure that we can do all the operations that we need to do without the cubits sort of decoheering, because we take too long to actually tell it what to do.
STFC-RAL-CR03 R61: I mean, that's it. You're proving that that doesn't work?
STFC-RAL-CR03 R61: Well, I think… I'm gonna assume that I'm doing it wrong, initially. I'm gonna go, well, it's… it's…
STFC-RAL-CR03 R61: It's not working just because we're… the coherence time that we have on the machine at the minute is
STFC-RAL-CR03 R61: Still quite… Oops.
STFC-RAL-CR03 R61: And what might be some older machines that are better at this?
STFC-RAL-CR03 R61: And it may just be that there's one clever way of doing it. So we're already working on things where, for example, not all the interactions are important, so we could try and prune some of this stuff down. There's…
STFC-RAL-CR03 R61: different ways in which we could reformulate the propagation, for example. So there's… there's a few… quite a few tricks that we can still, you know, we're not out of tricks yet.
STFC-RAL-CR03 R61: But it's a very… so the idea is, can we actually do it at all? You're right, it may be that we get to that and go, actually, this is…
STFC-RAL-CR03 R61: Too complex a problem.
STFC-RAL-CR03 R61: For the hardware that we have at the minute.
STFC-RAL-CR03 R61: But I think, yeah, if you don't try a slow sniper, we'll never know what the right said.
STFC-RAL-CR03 R61: Oh, sorry, you do.
STFC-RAL-CR03 R61: So I… I first wanted to ask, like, how much energy is actually transferred by the nodes interacting with the,
STFC-RAL-CR03 R61: Super.
STFC-RAL-CR03 R61: so, we think that when
STFC-RAL-CR03 R61: In sort of the later stage in, when you're…
STFC-RAL-CR03 R61: creating the protonutral star, so the final star. That is actually quite a lot of energy that is… that you get from
STFC-RAL-CR03 R61: Essentially, gravitational…
STFC-RAL-CR03 R61: collapse. And most of that energy, in the estimation so far, at least 90%, comes off as
STFC-RAL-CR03 R61: is going into the neutrinos. How much is then taken back.
STFC-RAL-CR03 R61: is… I think the idea was…
STFC-RAL-CR03 R61: So you can… you can calculate, sort of foods and rates and things like that, but essentially, all you need is to have enough energy to, sort of.
STFC-RAL-CR03 R61: Tip the shock over to then…
STFC-RAL-CR03 R61: get it to explore. So it's not that you need necessarily a lot, right?
STFC-RAL-CR03 R61: Astrophysical units, right? A lot is probably quite a lot, but you still, you know, you don't need to have, like.
STFC-RAL-CR03 R61: 10 to the 46 joules.
STFC-RAL-CR03 R61: So it's in there for it to happen. You are… your shock is coming out, your informing matter is coming, so you're so… essentially, you just need to disrupt the equilibrium enough, then it just goes, okay, so essentially bubbles out. But there's loads of things
STFC-RAL-CR03 R61: hidden behind that that I haven't talked about. For example, we know that these explosions are not symmetrical at all. They end up being really stretched. You know, all the simulations give you very… and even the observations give you very weird remnants from this.
STFC-RAL-CR03 R61: And so there's some preferential… I mean, it could be that you just… like a bubble, you just burst one part, and then that's maybe what's causing it. We don't know. It could be that it's just due with the structure inside it, etc. That would also impact. So it's, good as…
STFC-RAL-CR03 R61: it's good enough as long as it can just pass through some kind of threshold. Exactly, yeah, yeah, exactly. It's not… so what we're saying is it's not the neutrinos that are completely
STFC-RAL-CR03 R61: driving the explosion itself. There's already some things happening to it. The neutrios might be there to help break the deadlock that you have, because, I mean.
STFC-RAL-CR03 R61: Energy transfer through neutrinos Yeah, we're all kids then smarter, but it's not all so… super efficient.
STFC-RAL-CR03 R61: Right. Although, all the words.
STFC-RAL-CR03 R61: You wouldn't need the big detection and go, oh, yeah, look, super cross-section, we'll get those materials.
STFC-RAL-CR03 R61: No, you go ahead. Thank you.
STFC-RAL-CR03 R61: I actually had another question about the quantum computing part. Yeah. So it's more of a confusion, because when I've
STFC-RAL-CR03 R61: I learned about quantum computing, it was usually, at the middle state, it's fine to go superposition, but at the final state, you have to, project it to, 100 or a 0. That's right, yeah. But it seems it's…
STFC-RAL-CR03 R61: kind of something.
STFC-RAL-CR03 R61: completely opposite of that. No, no, no, no, I think here you… ultimately, you still have to measure. You still have to say, the energy, you're measuring the few bits, and you'll get just 0 or 1.
STFC-RAL-CR03 R61: The whole thing is, what they do in quantum computing is that they're trying to, sort of, engineer the superpositions or the entanglements so that they enable you
STFC-RAL-CR03 R61: compute what you want. It's…
STFC-RAL-CR03 R61: The tricky part, I think, is that a lot of people using 14 computers are trying to
STFC-RAL-CR03 R61: simulate, or to do normal computing with it. So they're like, oh, they're representing numbers. But actually, the easiest thing for quantum computers to do is
STFC-RAL-CR03 R61: just to do some quantum physics, because that's actually what it does. So, in all case.
STFC-RAL-CR03 R61: we're making something more like an analog, I suppose, of your neutrinos, and you say, well, yeah, so we don't need
STFC-RAL-CR03 R61: We just basically… it's a bit as if we had a detector there, and we say, well, is it an electronutrino or other neutrino? And then we just measure them, and all we need to do is just engineer, sort of, the dynamics, essentially, inside the multiple computer.
STFC-RAL-CR03 R61: I want it to be, you know, headline-catching, I would say. A super number inside a quantum computing. That's really important.
STFC-RAL-CR03 R61: Yeah, I mean, I got the impression that it was sort of like a miniature hardware Monte Carlo device. Yeah, well, at the minute, that's probably what it looks like, but hopefully we can make it a bit more…
STFC-RAL-CR03 R61: For purpose.
STFC-RAL-CR03 R61: Okay, Bob? Yeah, a couple of points. In the quantum, calculations you're doing, you're… you're representing neutrinos with qubits. Yes, and you were always, they were…
STFC-RAL-CR03 R61: in base. So you did mention that there's a randomness to it. Yes. There's a random phase approximation that you didn't…
STFC-RAL-CR03 R61: you alluded to it, but you didn't actually discuss. Yes. So, is that where the problem arises, in not being able to, let's say, get the right result? Yeah, so when you do it… so, in…
STFC-RAL-CR03 R61: The classical approximations, well.
STFC-RAL-CR03 R61: It's not… I'm calling it classical, as in, we're not going to do computer versions. You would…
STFC-RAL-CR03 R61: typically use RPA, so you use a random phase approximation, or similarly, a sort of mean-field type approximation, where you're going to say, okay, that neutrino sees all the others, they'll wave… you know, you essentially have a separable wave function.
STFC-RAL-CR03 R61: Key here is we don't need to have a separable wave function, so we could generate a state that is
STFC-RAL-CR03 R61: all two materials all entangled together, not a separable state that you can't actual out, basically. And then we can propagate that state and see what the end result is. That's, I think, the difference between doing it that way or doing it using RPA or some of the other methods is
STFC-RAL-CR03 R61: At some stage, you're sort of factoring out part of your system so that you can treat it.
STFC-RAL-CR03 R61: Yeah, thanks.
STFC-RAL-CR03 R61: One more point. I mean, in the neutrino problem, I mean, it was recognized that about 1% of the neutrino energy coming from the core has got to be dumped around about the shock wave, so that's the main problem. How does that neutrino energy
STFC-RAL-CR03 R61: communicate with the matter behind the shock to revive the shock. So you've got to raise the temperature by about, say, well, up to about half an MAP in the material that is behind the shock. Yeah, exactly. So that's the big problem. And you also have only
STFC-RAL-CR03 R61: pretty much one channel that really interacts with radioactive neutrinos, so if you… if you sort of… if your oscillations are, sort of.
STFC-RAL-CR03 R61: dampen that much that all your electric neutrinos now become other neutrinos. You can't… And I think that's… that's the point I would try. What's interesting here is we're seeing the ones that would have the high energy, they basically just
STFC-RAL-CR03 R61: ill. And you're, okay, so then it's not planned, but how much energy is then left?
STFC-RAL-CR03 R61: in the sort of low-energy nutrients to actually do that, that we kind of solve the emissions overall. So I think that's what we're trying to… what we're trying to drive up for us, to try and see, is it then going to be
STFC-RAL-CR03 R61: really abide for the split, although we have, like, a distribution, and is some of that removed from this by your, your sort of bluefield approximation?
STFC-RAL-CR03 R61: Any questions from Tzu?
STFC-RAL-CR03 R61: Please unmute if you have anything.
STFC-RAL-CR03 R61: Looks like not. Anything else from room?
STFC-RAL-CR03 R61: I would hold my questions for later lunch. Please do feel free to join us for lunch, and we'll be happy to interact with you.
STFC-RAL-CR03 R61: So, let's thank our speaker.
STFC-RAL-CR03 R61: Thank you, Emma. Thank you.
STFC-RAL-CR03 R61: Oracle.