The New Quantum Era

Kevin and Sebastian are joined by Grant Salton, a quantum researcher at AWS, who helps us understand a recent paper from Google and Caltech whose authors describe a simulation of a wormhole on Google's Sycamore quantum computer. The paper stirred some controversy and push back on the misunderstanding of the claims being made, and Grant walks us through a sub-domain of quantum information science called "it from qubit," which seeks to bridge elements of astrophysics with concepts from quantum information.

Mentioned in the episode:
The Nature paper from Google and Caltech describing the wormhole experiment and findings.
Some context from Caltech blog.
John Wheeler's paper: "Information, Physics, Quantum: The Search for Links" which coined "it from bit."
A BBC article describing the "quantum hair" solution to Hawking's black hole information paradox.
The Edge of All We Know, a terrific documentary that traces the efforts to solve the information paradox in parallel with the effort to capture an image of a black hole. 

Creators & Guests

Host
Kevin Rowney
Host
Sebastian HassingeršŸŒ»
Business development #QuantumComputing @AWScloud Opinions mine, he/him.
Guest
Grant Salton
Composer
Omar Costa Hamido
OCH is a performer, composer, and technologist, working primarily in multimedia and improvisation. His current research is on quantum computing and music composition, telematics, and multimedia. He is passionate about emerging technology, cinema, teaching, and performing new works. He earned his PhD in Integrated Composition, Improvisation and Technology at University of California, Irvine with his research project Adventures in Quantumland (quantumland.art). He also earned his MA in Music Theory and Composition at ESMAE-IPP Portugal with his research on the relations between music and painting. In recent years, his work has been recognized with grants and awards from MSCA, Fulbright, FundaĆ§Ć£o para a CiĆŖncia e a Tecnologia, Medici, Beall Center for Art+Technology, and IBM.

What is The New Quantum Era?

Your hosts, Sebastian Hassinger and Kevin Rowney, interview brilliant research scientists, software developers, engineers and others actively exploring the possibilities of our new quantum era. We will cover topics in quantum computing, networking and sensing, focusing on hardware, algorithms and general theory. The show aims for accessibility - neither of us are physicists! - and we'll try to provide context for the terminology and glimpses at the fascinating history of this new field as it evolves in real time.

E007
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Sebastian Hassinger: [00:00:00] The New Quantum Era, a podcast by Sebastian Hassinger. And Kevin,

welcome to another episode of The New Quantum Era. Uh, I'm Sebastian Hassinger. Hey, I'm Kevin Rowney and today we are joined by Grant Salton, who's a quantum research scientist at the Amazon Quantum Solutions Lab at Amazon Web Services and a colleague of mine, . I met Grant, uh, a little over a year ago when I joined AWS.

Um, and I've really enjoyed my, uh, interactions with Grant. He's very, very good at, um, sort of, [00:01:00] uh, explainers, I would say, and providing background and context for, for my limited, uh, kinda understanding of, of quantum information science. He, um, has a particular sort of, Focus in, in his background on what is termed it from qubit.

And so we thought he'd be a really good guest today to help us understand, uh, sort of the ramifications and context around a recent paper, uh, that Google and Caltech issued. Uh, that generated quite a bit of buzz and not a little bit of controversy. Yeah.

Kevin Rowney: A a lot of, a lot of splash in the media on that result.

I mean, maybe if you're a listener, you've, you've even saw that, that run on by these dramatic claims about, uh, wormhole and so forth. And That's right. A lot of, a lot of spin, uh, maybe some, even some marketing, who knows? Uh, but, but you what in digging into this subject in, in more depth, just on our own, and we re we realize there's just a vast amount of actually quite compelling, interesting, and substantial theory under the hood here that, um, I [00:02:00] found to be, um, rather intimidating at first.

I, I think Grant has done an excellent job on this episode of helping, uh, you know, make more clear, uh, what we're talking about. Even then, it's, it's some rather formidable mathematical abstraction. It. But, so I'm warn in the audience there is uh, there is some, some climbing ahead, but Grant does a great job, I think, right?

He really does a bottom line. Again, making it clear.

Sebastian Hassinger: Yeah, he really does. I really enjoy it. So with that, let's get onto

Cool. All right. So we're joined today by Grant Salton, who's [00:03:00] a colleague of mine. Um, we both work at Amazon Web Services on the Quantum team. And Grant, uh, is going to, uh, take us through some of the, uh, topic area of it from qubit, uh, which I think is, is particularly fascinating. So to start off with

Kevin Rowney: a cool, a cool and baffling topic.

So Grant, thank you. Yeah. Even more baffling in the

Sebastian Hassinger: usual quantum stuff. So yeah. To start with Grant, um, would you mind, uh, sort of introducing yourself and, and, and providing a little bit of like, it's always interesting to hear how people sort of got into this field and, and found their way to this sort of, uh, new amorphous, uh, area of, of development that is quantum

Grant Salton: technologies.

Yeah. Yeah. Happy to. And thank you so much for, for having me. It's a Sure. Good to great chat. So, um, I mean, I started, I started studying physics early on in high school. I'd planted , you know, going way back planned to do engineering. But, uh, I, I really got into to physics. At that stage and found it pretty fun.

So, [00:04:00] and as an undergrad I specialized in astrophysics with no focus on anything quantum, and always in the background, I was interested in something else. So I was trying to do astrophysics, but then focusing on, or start studying cosmology on the side. And I thought, all right, well let's do some grad school on this.

This is fun. So, uh, you know, wrapping up my undergrad, planning to do a cosmology, masters , I, I took a class in Quantum Information Theory, um, which was new for its time at the university where I was studying, and it was pretty fun. So when I started my masters, I thought, all right, well, I'm studying. Early university theoretical cosmology, but this quantum info stuff was pretty cool.

This quantum, you know, quantum physics. So let's try to get into that a little bit more. Try to see if I can find a way to put those two together. Um, and in Canada, whereas do my masters, you know, you've got two years. It's hard to get anything done in, in two years when you got classes and thesis, let alone trying to merge two things that don't seem to, you know, there's not as much traction.

Um, so I finished, I finished that up and I thought all well, uh, from there, let's, let's carry on. Um, but I'm really digging this quantum info stuff, so put [00:05:00] the cosmology side, so to Cosmo, to, to quantum info. And I did that as, uh, you know, full-time for, for PhD. Um, but always trying to, to find a way to, you know, bring it back to something else that I, I found was super cool.

Like, I like working at the interface between different, different fields and different topics. Applying the tools of quantum information theory to other areas of physics or using different types of math to solve problems in quantum info or something like this. Right. Just, you know, working at an interface between multiple things and.

Um, I did this, that was my plan for, for grad school, and I was very fortunate at the time that this, this, it from cubic collaboration sort of spun up around me and that I was sort of steeped in it by other people, with other people that, that were sort of like-minded. And it was just very, very fortunate timing for me.

And,

Sebastian Hassinger: and what, what was it, do you remember, what was, uh, sort of the initial hook for quantum information that sort of started to drag you away from Cosmo, ? You know,

Grant Salton: it's, honestly, I think it was just the way I would think about problems. Seem to make the [00:06:00] most sense in terms of the language of information, right?

Mm-hmm. Like I, I guess I'm one of these, these staunch supporters of the idea that it, that really information is, uh, it's not turtles all the way down. It's information at, at the, at the very bottle, at the, you know, when, when you get down to brass tax, it's information theory everywhere. Our reality comes from that.

So I, that seemed to make, you know, the questions made sense, uh, and the, and the approaches to solving them made sense. And it just felt like a very natural, beautiful, elegant way of describing, describing, um, interactions in

Sebastian Hassinger: physics. Do you think you encountered like Wheeler sort of it from bit before quantum information or quantum information and then sort of the it from qubit sort of thinking?

Or, or was there some, any sequence

Kevin Rowney: to that?

Grant Salton: The, I'd say, I'd say it was the, probably the latter. I mean, uh, my first quantum information theory exposure was through this, this really fun undergrad course. Maybe it was a grad course. I don't remember. I think I was auditing it either way. Um, And that was more just about understanding, like the math that's required.

Yeah. The d and matrices, that kind of stuff. And [00:07:00] getting into the, getting into some of the, the details, but not, not really with a focus on it from, from bit. Right. But nevertheless, it's, it's kind of there. Yeah. This makes sense.

Kevin Rowney: And, and I think, uh, just because this is a podcast on, you know, quantum computing and, you know, the, the numerous new results in quantum mechanics that are spinning off, I mean, such a cool subject, but I think for our audience, we might need to center right this conversation in a way that makes sense against current events.

I mean, the. The thing that, that we, that really inspired us to invite you on was that, that big new result right from Google around, you know, the quantum computing division, just speaking publicly about, you know, worm holes and so forth. It was a very, very confusing bit of, of press for us, right? And so we wanted to sort of dig into, into more substance on that.

And so I, I think a parallel development, we need to brief our audience. So maybe for insiders like you, it seems, uh, obvious and true, but this whole it from qubit movement has been a gigantic intellectual fountain, right? This just sort of like sprouted up recently with like super high-end mathematicians and physicists [00:08:00] collaborating on, I guess a brand new notion of, of foundations of, of cosmology related to quantum information science.

So there's these two big trends. This, this big splashy Google announcement and this huge intellectual movement. I mean, it do I do I have the description right in terms of the context that helps I think. Describe current events.

Grant Salton: Yeah, I mean, I would say that I'd say that it from qubit type, this intellectual movement has, yeah, as you say, it sprouted up somewhat recently and has included some of the, the biggest names anyway in physics as, as contributors.

Uh, and under that umbrella, that sort of way of thinking. There have been a lot of results that came out and I would maybe, maybe I would, maybe I'll take some liberties and classify some of these other things that more would topic please underneath as, underneath being in, uh, under that umbrella that, that way of thinking.

I mean, so it, it from Cubic is, uh, this is going back to, uh, as Smash mentioned, right? John, John Wheeler had this, this notion of it from bit that our reality is that [00:09:00] all of the things that we would call it are the stuff that that happens and, and the things we see. Those are at their core, really just manifestations of.

Of information doing, doing stuff. And um, that notion was pretty, you know, he had a lot of foresight and it was like 20 years later or more, right, that this started to started. People started to take this bit more seriously and he was saying it from it from bit, talking about classical information, really zeros and ones bits.

But, um, more recently people saying, well, the world is inherently quantum mechanical and the type of information that we really have as bedrock is quantum information. And this, the quantum systems have this different type of information that's not classical. Yes. And so this was now, it was gonna be, um, it from,

Sebastian Hassinger: from Cuban and, and Wheelers.

So that's a 1989 paper where he, he sort of introduced that phrase it from bit, uh, I've read sort of analysis that, that um, in a sense that shifted. Uh, the, the mission of physics from explaining, you know, the, the nature of [00:10:00] matter to explaining how we perceive, uh, nature, right? Yeah. Like it's, it turns into a system of understanding rather than a system of explaining.

Is that, do you think that's accurate?

Grant Salton: Yeah. I mean, yeah, to some extent. I think that's probably a fair statement, right? He, he's trying to argue really that, um, that way down everything is information and we just need to, we just need to pay attention to, uh, the information content of the universe to really understand what's going on and that a lot of these things are, are, um, manifestations.

He has this quote that I'm trying to remember off the top of my head, and I'm probably gonna get it wrong, or, you know, I honestly don't remember, but he, like, he's a hundred, he takes a hundred percent seriously the fact that, that the idea that, you know, everything we perceive is just sort of, That our reality is fully just perception of information.

Sebastian Hassinger: Right. Precipitator? It's a precipitory. Yeah. Yeah. Is

Kevin Rowney: is our, our, our world experience comes from these quantum and chemical observables, so to speak. And that, that the center of the theory is, and was it

Sebastian Hassinger: originally Yeah, quantum in, I guess it was, but [00:11:00] was it explicitly quantum in nature? And he was sort of saying like, you know, uh, like nature requires, uh, observation essentially in the way that, that we think about in, in inquiry information science

Grant Salton: terms.

I, I think, I think that's right. It's been a long time since I've seen this, but I think that, I think that's right. I mean, I think he's even talking about sort of the wave function and stuff in, in the abstract of that early paper. Right? Right. So, so he, he was saying, yes, you know, we have this quantum mechanical reality, but nevertheless, all of the things we see and all of the, the clicks of detectors and that kind of stuff, when we make measurements, this all boils down at their core to information.

And we, we just really understand things through that. So

Kevin Rowney: I, I think this is a really helpful, I think, uh, way to, um, for our audience understand just the basics of that whole, that whole movement. Sure. I mean, I'm wondering, uh, grant, do you, can you help our audience, um, you know, uh, see with more clarity that, that recent result from Google, because that, you know, uh, there was just widespread, right?

Both criticism, right, of, uh, as if it said like, so much hype, but also it feels like there's an [00:12:00] understory, which is, you know, uh, compelling and real. I, even, even my, my son, my 17 year old son, he was like, dad, I, that Google result. That's really it. And he's like, is there a connection between entangle bits and wormholes?

I'm like, whoa. Good questions young man. I don't really know. I ,

Sebastian Hassinger: I do wanna say it feels like, uh, the, the, the concerns about this paper are really around the way the paper was conveyed to the general public, right? Yes. You have headline saying like, Google researchers open wormhole with quantum , which I love By the way, before you, before you jump in, Scott Ericson writing, uh, you know, the, if this experiment has brought up wormhole into actual physics, physical existence, then a strong case could be made that you two bring a wormhole into actual physical existence every time you sketch one with a pen and paper.

Kevin Rowney: Classic. Classic Aaronson too.

Grant Salton: Yeah. Yeah. Um, Yeah, I, I, I [00:13:00] hear a little bit of, of what you're saying there, right. So just to try to put some of this into, into context. Right. Thank, so there, there was an experiment this year where, um, some, some researchers from several different universities, uh, and, and also Google, they used a, they used currently available quantum device that Google has to run an experiment on, I think nine cubits.

Um, and some, some number of, of gates, you know, quantum, quantum operations. They were apply to those cubs. And what they were doing was they were trying to implement a proposal, uh, an experimental proposal that was, that came out a couple years ago, um, that would try to demonstrate a phenomenon that. Looks like it would be a wormhole in some other description.

So let's, let's, let's back up a little bit here. Like , we need to sort of set this stage

Sebastian Hassinger: and how does that, how is how my first read was, well isn't that just teleportation, which is demonstrated all the time with, with, uh, you know, Cubs, right? Yeah. Kind

Kevin Rowney: of To some

Grant Salton: extent. Yeah. But, but a little bit of a [00:14:00] different kind.

So, so it turns out there are different types of teleportation, right? So the, so all of this, so let's, let's be clear here. That, that, that there were no, there were no war holes. There were no actual war holes. There were no black holes being created. Yeah. I mean, spoilers. Sorry. Yeah. The,

Sebastian Hassinger: it's sort of like when, uh, they turned on the, um, which one was it?

Not, not, uh, I mean, obviously the. Uh, the European one, but there is an American collider that was turned on and they were like, there's a small chance it'll open a, it's by of the

Kevin Rowney: universe. Yeah, exactly. .

Grant Salton: And it did not press pause to make sure the theorist said to make sure. Yeah, that's right. Exactly right.

Uh, yeah. So here all, all of these things are, are being done in the context of, of something called holography. So this is a description of, um, this is a, this is a, a way of describing a, a physical system that is, uh, that's some kind of quantum quantum system that has a different description in terms of a non quantum system that looks like it has gravity.

Um, [00:15:00] more concretely that like there are different, there are different, um, proposals for these holographic systems. And there's some concrete ones. One, the, a famous one is this Ad s CFTs. That's right. Anti space, conformal field theory. Don't need to know about the details. But the point here is that there are, there are two.

Pretty different looking systems. One of them is regular old like Einstein Gravity basically, uh, the sort of thing that people that, that Einstein would've called in general relativity in a, in a space time that has a particular structure, has some kind of curvature. And that purely gravitational system is dual in a sense, has another completely, uh, different description.

But that is sort of in one-to-one correspondence in, in some particular sense to a system that has no gravity. It just is a, it's a special type of quantum field theory that has a lot of symmetries called conformal field theory. And those two things that look very different, the, the conjecture was that they are really kind of the same thing in just different [00:16:00] language.

And then things that happen and, and prop properties and observables and physics in one system have a different description than the other system that there's a dictionary between the two. And you could sort of translate back and forth. Um, And that sounds, you know, on the face of it a little bit a a little bit absurd, but there's, there's a lot of evidence for this.

Mm-hmm. And there's a lot of really nice math and some, some very simple cool looking pictures that we, uh, we, that don't, don't sort of translate here, but that, that make it look pretty, um, pretty nice. Where to some extent, like there's this, this analogy that you can draw in some set of coordinates. You could draw this, this space time, this antier space time.

It looks sort of like a cylinder. Um, and the conformal field theory. The cool thing about it is that it, it has one fewer spatial dimensions. So if you had, uh, maybe a gravity in three dimensions, then this conformal theory is only in two dimensions. So it loses a, loses a space, a spatial dimension. And so, um, in some coordinates you'd have this space time as [00:17:00] a cylinder and you'd have the conformal theory as just sort of like the boundary of that cylinder.

And so the analogy that some people like to make is that, well, think of that like a soup can, there's all this crazy stuff happening inside the can of soup . There's, you know, there's actual chunks of, of meat and vegetables floating around and it's moving and they're, they're bumping into each other and all of the crazy stuff that's happening inside the can of soup is actually just as well described by the properties of the electrons and all the little particles that are happening that, that are zipping around on the surface of the can.

Mm-hmm. in that metal. Um, and. On the face of it is, is why is this is called holography to some extent because, you know, you lose a spatial dimension. It's a projection up inside is is also apparent on the surface. Oh,

I

Kevin Rowney: see. Is is it

Sebastian Hassinger: also, right, like is it also accurate to describe that as sort of you can you, can I interpolate from, from really precise measurement of everything that the can is, you could figure out, you can interpretate what the contents of the can are just by, by the way that they're interacting with the can itself.

Is that, [00:18:00] is that another way to describe that? Y Yeah.

Grant Salton: I mean, and in fact I'd say it's, it's even stronger than that though. Right? Okay. Like the, the, um, That all of the things that happen on the can are dual in some sense to what's happening inside the can and vice versa. Right, right, right. And so everything that's inside the can is represented somewhere on the boundary, on the, on the, in the metal.

And, uh, everything that's happening on the, on the metal is also happening inside the

Sebastian Hassinger: can. So in some language, like the, the, the, the, it is the soup and the qubit is the information about the soup that the can contains. , is that

Grant Salton: Yeah, . Yeah. Yeah. Um, this is sort of like a more comfortable torture metaphor at this point, but

Kevin Rowney: pretty, pretty good Sebastian realm

Sebastian Hassinger: hungry now though.

Grant Salton: yeah. Some, some point, some bread is gonna enter this discussion, but so we, we, we have this, this cool description of, of the stuff that. In a particular type of space time that this thing that, that I mentioned is called anti sitter space, which doesn't have the same structure as [00:19:00] our universe. Uh, but it's still nevertheless like a, a cool toy model.

We have another description of all of the weird gravitational physics that's happening in there, equally well described in terms of, uh, another very different system, this conformal field theory or some other kind of quantum system. And so this is, this is the sense in which you can say, I'm going to probe some properties of what's happening in the, in the gravitational system by looking at a set of, of quantum degrees of freedom that are different.

And the, the extension of this is to say, all right, well, I can represent some of the, the physics that's happening in this kooky conformal field theory. Um, just in terms of some qubits on a, on a quantum computer. Mm, I can represent a lot of the physics that would happen in that type of field theory. Um, just in terms of some interactions, some gates that are applied to, to qubits, provided I do this carefully.

Um, and now the, now the analogy is, all right, well, if I have, if I can study the physics in my qubits and say that this has a dual description in [00:20:00] terms of gravity, then I should be able to describe the outcome of what I'm gonna see in my experiments on the quantum computer in terms of the, the thing happening in space time and, yeah.

Got it. So it doesn't mean that there's like, that I'm actually creating , right. Uh, another universe of, of stuff. It just means that it's, I have another mathematical way of describing these things. That's super

Sebastian Hassinger: interesting. I mean, is it, is another way of saying that, that, that if there were a tiny wormhole beside a quantum, you know, in, in a quantum system beside a quantum system, or, you know, if there were soup in the can, you would expect to see those, those, uh, phenomena, um, in the, on the surface of the can.

Right. That's right. But seeing the surface or or replicating the, the results on the surface of the can doesn't make the soup appear . Is that, that's,

Kevin Rowney: that is right. That's

Grant Salton: true . That that's true. And in fact, also, you know, it's not necessarily like when you, when there was a, there was a step that I, that I made there where I said, all right, well, I can try to represent some of the physics in this, uh, [00:21:00] on the, on the boundary of the, of this can in terms of qubits.

Unless I'm doing that very carefully and I'm making sure that I'm actually representing the right physics, I'm not even going to be able to say that there's a dual description in terms of gravity. So there wouldn't be a, a wormhole somewhere. Um, unless I'm sure that I, that I'm doing the right experiment and I'm making sure that the physics is doing is behaving as I would expect.

Sebastian Hassinger: And how does the, the, how does that experiment or that line of thinking sort of deal with the, the, the lack of, of gravity? Like, you know, we don't have a connection between, uh, gravity in a, in a, in a, uh, in a macro, in a cosmological sense and, and the absence of it in a quantum system, right? We don't know why they're, why gravity doesn't translate over.

We don't know how it does. Is that, is that right?

Grant Salton: Well, okay. So I, uh, maybe, maybe just as, as part of my answer, I, I, let me preface this by saying like, so why might we actually. Care about doing this, this mapping between these, these two systems? Like what, [00:22:00] in what sense? Like what do we actually gain from saying, oh, well I have all of this stuff here, but I can just describe it a different way.

Why, why is that a thing we care about? Um, the reason is that some of the things that are easy to talk about on one side of this duality, like some things that are really easy to, to describe and gravity correspond to things that are really complicated, which we cannot write down in nice, simple terms, right?

Yeah. And the quantum side. Yeah. And things that we can describe very simply and clearly, and things we understand very well on the quantum side often correspond to very complicated phenomena that we don't really understand on the gravity side.

Kevin Rowney: And that makes, that makes perfect sense. I mean, in a lot of, of mathematics results in recent decades, I mean this, they, you finding essentially isomorphism with different geometries, uh, has led to gigantic breakthroughs in numerous different domains.

So it, it makes exact sense now. Yeah. That, you know, if you could find a, uh, a way to connect these two abstract models, you could, you could really illuminate lots of the landscape. This is, this is, this is useful. Thank you. And so this is,

Grant Salton: this is the sense in which, um, we can, we [00:23:00] can try to understand phenomena that looks really complicated and we don't really have a good sort of grasp on it on one side in terms of something that we really do understand very well.

Uh, cause that is a very simple description on the other side of this duality. Um, and this, this, this comes into, um, uh, the description of what's happening. You, you mentioned earlier, teleportation Sebastian, the description of what's happening in this, this experiment has a, in, in certain perimeter regimes has an even better descript, has a simpler, easier description in terms of particles moving through a wormhole on, uh, on the other side.

Whereas it looks like some complicated quantum dynamics on the first side. I now realize that I've forgotten what your actual question was, .

Kevin Rowney: No, it's good. This is, it's fantastic this material because if you're, you're getting right to the, the core question is how do we, uh, describe in some, you know, deeper way the connection between this, this, uh, wormhole abstraction and issues of entanglement and teleportation.

So you're saying there's these two [00:24:00] different mathematical abstractions which have a tight interrelationship. I it's almost an isomorphism it sounds like formally. Yeah. And, and if you model in dec sitter space, the notion of, uh, of a wormhole, it's, it's isomorphic representation. Sorry about the abstraction there.

It, it, overall, overall on the quantum information side, uh, seems to exactly map two issues of entanglement and teleportation. Did I get that right?

Grant Salton: Yeah, exactly. And so, so let's, let's, let's, um, frame the, the question here, right? So. Early on, right? We have this, we have this duality between gravity and this type of quantum system.

Yeah. And people were saying, well, look, it turns out that actually if I have two of these universes, two of these, uh, these space times that are sort of separate, that's, that's fine. I would just say, okay, well I have also then two of the, the metal cans or something like that. Sure, sure. But now, since those metal cans are quantum systems, what happens if I just put them in some kind.

Really cool quantum state. I say that [00:25:00] there's entanglement between them or something like that. Yes. What does that look like on the gravity side? And people managed to work this out. They figured out through that dictionary what this looks like in it. It looks like you just sort of stitched together the two space times behind a black hole so that you know there's a black hole in one and a black hole in the other, and the interiors of those black holes are somehow stitched together.

And, you know, what does that mean? That's one of the questions that this different community wants to get to. Um, but it looks like a wormhole where if you're in one side, one universe and the person in a different universe, and they, they jump, they both jump into the black holes. They could talk to each other once they're behind it, but they could never transfer it to the other side.

And then some, some smart people said, all right, well actually it looks like actually what happens if I apply some, if I apply some gates, some operations on these two quantum systems, the two metal cans that sort of spann both sides. Then it looks like it when they, they went through this mapping and said, just tried to describe it in terms of gravity.

Said, oh, it looks like actually we open a wormhole that a particle could go through. Wow. And. There's, you know, there's some, there's some [00:26:00] cool, uh, cool math to, to describe this. And you have to do some, you, you know, and this isn't something that we're gonna be doing in like, in the real world because this is, this is two toy models of gravity and we're applying.

I

Sebastian Hassinger: saw, amen. I know how this works.

Grant Salton: So, but, but nevertheless, right? Like, mathematically, this looks like a wormhole that that opens up in such a way that a particle could go through it. And then there was a

Kevin Rowney: question, well,

Sebastian Hassinger: what does, but Grant, is it, is it, is it the particle or the information that represents the particle? Well, uh, is it the IT or

Grant Salton: the qubit?

right, exactly. So, yeah, I mean, uh, Are those different things? I don't know. . Yeah, we're getting a little Phil Philosophical.

Kevin Rowney: Yeah, we're going to epistemology. Yeah. Right. Yeah, yeah, exactly. So dangerous

Grant Salton: territory, , right? We'll, change topic for

Sebastian Hassinger: No, I love this topic. Are you,

Grant Salton: so the, so the, uh, the question then was, all right, well, I managed to open this wormhole, um, on [00:27:00] the, in this, these toy models of, of gravity.

What does that, what is the act, what's the description of that on, in terms of the, the physics, the, the quantum physics? Like what is the dual description that we can understand in terms of qubits and gates acting on them on a quantum computer and the gravity side? All right. I made it sound a little bit, it sounds kind of, uh, kind of complicated.

I've got these entangled space time and stuff. It's not so bad, right? There's just, imagine a wormhole somewhere and you can send a particle or a person or a bit of some information through it that you can, you can visualize, you just, you know, throw a book into a black hole and it pops out the other side of a different black hole.

The dual description of this is some complicated, well, it's not so complicated, but, but like some, uh, some particular protocol that needs to happen on the, in these boundary quantum systems, right? You have to do some kind of chaotic dynamics. It's really, really messy. Um, you have to apply these gates between them and, and suddenly the information comes out and it, it looks, it looks sort of, uh, miraculous to some extent.

It's almost like you're [00:28:00] saying, all right, I have, um, Screaming to a hurricane, my message, the words I say, just get completely, uh, uh, mixed and, and scrambled up in the hurricane. And then somewhere on the other side of the, of a football field, my message just suddenly comes out.

Kevin Rowney: It somehow gets reassembled and boom.

Spoken clearly,

Grant Salton: yes. With without any, any, any understanding. And that there's some weird, you know, like obviously something interesting is happening there. And you say, well, what, how can I describe that? And it turns out that the, you know, in, in the, uh, for the protocol I described in the, on this quantum device or the system that we're talking about, the most natural, or the e I shouldn't say natural.

The simplest description of what's happened here is that in, if you think of this as a gravitational system, it's just a particle moving through a wormhole. Hmm. Wow. And, and so this was what, what the experiment was trying to, to do. I mean, they, they had to try to find the, the smallest system that they could represent, um, that would nevertheless have the physics that they needed to do.

And they used some machine learning techniques to try to find a smaller [00:29:00] system. Um, With simpler interactions that still behaves as they wanted. And then they, and then it was about just implementing the protocol. Hmm. And to be clear, just, you know, stating it, once again, nobody opened any wormhole anywhere,

And also it's a, it was a small enough, the point was that they wanted to, they needed to bring this, the system size down small enough that, that you'd still be able to see the signal that this was working, um, right through the noise of the, the, the fact that these are messy computers. So

Sebastian Hassinger: that's what I was gonna ask.

So you said there's, you know, chaotic dynamics. So the, you used the hurricane as the example. So were they, were they. Purposefully sort of trying to create those chaotic dynamics Yeah. In their circuit or were they using the noise of, of a n machine as uh, to, as the stand in it for the hurricane, because it is sort of a hurricane of noise.

Yeah. Yeah.

Grant Salton: Yeah. Okay. Uh, uh, uh, no. Yeah. You sort of want a hurricane in a different sense, right? You need the chaotic dynamics to really mix the information rather than just You want it to Right. Dissipating mix it in a Exactly. [00:30:00] You want to keep the information there rather than let it leak out into the environment.

Yeah. Yeah. But you want it to be all spread amongst the different

Sebastian Hassinger: cubs. Right. I guess that's true. Noise in a, in a current quantum system is actually like leaking into the outside environment, which makes it just go away, essentially. It doesn't

Grant Salton: have to be Right. Like you could have unwanted coherent noise between qubits.

You could do this, but, but you know, the net effect and the, the overwhelming effect for the time, for, for right now, current generations. Random.

Sebastian Hassinger: Yeah. It's leaking. Cool. So, so then they, they created, uh, this chaotic dynamic. Uh, sent the information into it and then the information appeared on the other end of the, of this chaotic dynamic.

Is that That's right.

Grant Salton: Yeah. Yeah, that's right. You have a, you, you sort of have a, have a bunch of qubits. Um, you're gonna think of half of them as one side of the wormhole, and the other half is the other side of the wormhole. You apply some chaotic dynamics, scrambling dynamics of the term scrambling that we like to use.

Um, and then you have to do this, you have to do this interesting interaction [00:31:00] between the two sets of cubits that I mentioned that corresponds to the, in coming back to the gravity side. That means that corresponds to acting jointly between the two different space times, or in the field theory example, acting with some two-sided operator.

But, um, in the, in the quantum computer means applying a particular, particular, uh, gate to a large subset of the qubits. And then there's some more, uh, chaotic dynamics that happens. Some of these are sort of forward evolution and others are backward evolution, but. In the end, it's still all kind of random scrambling dynamics and you find that the signal sort.

Returns. I, I mean, I mean, in many

Kevin Rowney: ways this is really such an impressive tour to force, right? I mean, there's like all, all this, you know, really powerful underlying mathematics of these, uh, these, the ice forces between these, these systems. This visionary concept of how epistemology right of, of cosmology can work.

And, uh, just these really cool efforts at, at Google and, and the team that surrounds them around these quantum computing circuits and machine learning [00:32:00] models to simplify it enough. I mean, wow, it's just so impressive. So, I, I don't wanna sound too crass here, but I'm just trying to, uh, help, help us get to, you know, bottom lines on I, is there, is there a, a way that there's commercial applications of these new results or, you know, new conclusions about science that, uh, we could reach or feel more comfortable with?

Because, I mean, in some ways, one could sort of critique this as sort of saying, well, look, there, there is a well known isomorphism, and then we did it on the quantum computer. It just, maybe that verifies the theory, but is, I mean, is it, is it a deeper breakthrough than that? Uh, help, help us understand Sure.

The merit, the significance of the result.

Grant Salton: Yeah. I mean, I would say, right. It, it's a small enough circuit that, uh, it's nine cubits. So we can, we can simulate this on our laptop without the Yes.

Kevin Rowney: Um, oh yeah.

Grant Salton: Okay. Yeah. So, so we knew what the result was going to be, right? Like we have Right. We have theory that tells us exactly what the results should be.

And this was an experimental demonstration that sort of validates the Yes. The theory that we expected. Yeah. So from this specific experiment, we didn't [00:33:00] learn something new. This was sort of a, a, this was a proof that, or this was an experimental demonstration of what we were, what we were, that, that it works

Kevin Rowney: as expected.

Yeah. Re reproducibility, right. Of results. Really important for science. Yeah. Crucial. Yeah. Yeah.

Grant Salton: Um, there was some, there was sort of like a newer component to this, which was that the machine learning, right, like the, in order to. A small model, a small, uh, something that would run on a quantum computer. You could take the, you could take the kind of dynamics that we need, the kind of system we need, and it's sort of, it's a bit larger.

So they had to go and find a smaller subset of this that, nevertheless, Maintains the properties of the system, right, that they wanted to simulate in a smaller set of degrees of freedom. And so they, they were training in such a way that they, they were able to bring down the total number of qubits and operations while still preserving some of the type, some, some of the properties that are needed.

Which was, which

Kevin Rowney: is, which was such a cool, uh, such a cool way to approach that. I mean, it's reminiscent of a lot of the work that was done in, in Spintronics recently, right? Where they're trying to figure out like these new exotic computer architectures, how to simplify the underlying circuits [00:34:00] using, using ml.

I mean, really, really novel and interesting.

Grant Salton: I think there's, yeah, I think there's a lot of work that can be done, uh, using classical machine learning to mm-hmm. to bring down the resource costs in for, for quantum computers and things like that. I think that, so yeah, there's,

Kevin Rowney: there's huge commercial applications there for the future.

Sounds like. Yeah. Down the

Grant Salton: road. Yeah. Once we have, once we've got these, these, uh, these devices in the, let's say the medium term, once they're large enough, we can do something cool, but nevertheless not sufficiently large that we have an unlimited number of resources. We're gonna have to find ways to bring down our, our resource costs.

Yeah. I think, I think that, you know, that kinda idea has some, has a merit. Um, so in, so, so in this, this specific experiment, I would say, you know, we didn. We didn't discover something that we had not seen before. This was a, this was a verification of the theory that, and, and nevertheless, you know, you could simulate this on a laptop, but as for future generations of hardware come online, we could start to modify the experiment such that we are probing things that we hadn't tried before, and see if we can understand something [00:35:00] new about, let's say, quantum gravity in this antici space, this, this toy model that we, we like.

Um, and that could start to give us some, some new instances that maybe we hadn't thought about in the past. Pretty interesting.

Kevin Rowney: And also in terms of theory in, in physics, I mean, this, this, this, this does not give more momentum to the so-called, uh, er, e p R conjecture. I mean, I, I guess that's one of the major, um, conjectures by Suskin and, and others around the interrelationship between entanglement and advanced gravitational theory.

Yeah. Does, does this you think maybe advance that cause at

Grant Salton: all? Um, so for, for, for, for those who might not be familiar. Right. So this ER equals epr. This is a, this is a claim that. That worm holes or, uh, or connections between distant re potentially distant regions of space time have to do with entanglement in some underlying, um, quantum description of that space time.

And, you know, the, the concrete realization of this in this a d s dft, uh, tin can do cor uh, correspondences is what I mentioned [00:36:00] before, that if you've got two of these space times that share that are stitched together behind a black hole that looks like a wormhole that corresponds to an entangled state on the boundary mm-hmm.

um, that's a necessary ingredient in this experiment. And this whole I see. Whole thing. Oh, I see. One of the, one of the starting points for the, for the, the protocol, this quantum protocol, is to construct a. Highly entangled state that looks kinda like a maximally entangled state, but where, you know, um, which, which has, you know, the most amount of entanglement between the different sides, different constituent parts.

Um, but here the sort of the amplitudes, the terms in the, in the sum sort of decay according to some distribution. And it that looks like, um, that that particular state that you have to construct is the thing that has as a dual gravitational description. A non-reversible simple wormhole where you just take two black holes and you stitch there behind the horizon regions together.

Hmm. So that, that is sort of a, that is epr, R er equals EPR at work. And this acronym as well, by the way, is, is like [00:37:00] Einstein Rose and equals Einstein Pesi Rolls. And one, one of those two, two of them did, two of them talked about wormhole, uh, worm. And two of them, three of them talked about

Sebastian Hassinger: tanglement, not the actual humans equaling each other.

Kevin Rowney: just to be clear.

Sebastian Hassinger: And, and, um, uh, you know, bringing Einstein and Einstein into this and, and the connection to Hawking and the information paradox of black holes. I mean, that, that was. I mean, is that result that there was that sort of breakthrough paper that sort of culminated the, the search for the, the solution, the information paradox that, that, uh, basically described as sort of, uh, the, the information being turned into hair around the outside of the black hole that got reconstituted as the black hole evaporated.

And in fact, that was the, when you were describing it from qubit, uh, to Eddie Farhi at, uh, Q2 B last year, you used that metaphor of the, you know, yelling into the hurricane and then having the, the words reconstitute as the [00:38:00] hurricane died down. It, it, so there's clearly, there's some kind of combination between the solution, the information paradox of black holes and, and this experiment.

Is that, is that right? Um,

Grant Salton: and this experiment, Hmm. I'm not, I'd have to think about this a little more. Mm-hmm. , I mean, I will say that, right? Like one of the, one of the. Crowning achievements of the IT from cubitt collaboration that sort of happened was, were a couple of papers that, or a series of papers kicked off by two, that that gave more credence to the idea that information is not really lost from black holes, right?

Mm-hmm. . Mm-hmm. , like, there's this sage old information paradox that as you, as a, you throw information into black hole, it radiates it away. And purely thermal hawking radiation, that doesn't tell you anything about one in what went in, but as it loses that information or that energy, it shrinks and eventually disappears.

And so information seems to be lost in black holes, violating quantum mechanics. Um, I mean, at some point there were, there were, uh, Hawking would, I think himself said that this is, this is likely not [00:39:00] actually gonna happen. The information does come out mm-hmm. , but in, in this, this, uh, holographic quantum gravity toy model, there, you can see this a bit more explicitly that, mm.

You can say, all right, if I had a black hole in my space time, I can talk about the dual description in the, in the, the gra in the quantum sense. And I can say, is there a way in which I can, like, how much of the interior space, how much of the space time can I recover? Can I talk about on just the boundary?

And it looks like for the most part, you can only really talk about the, the stuff that's outside the horizon. Mm-hmm. But I guess a series of papers, they found another way, another description where you are able to say, aha, if I, if I am able to capture the information that comes out, sorry, the, the radiation that comes outta the black hole and I lock it away, I don't really need it.

Um, but I, I, I treat the fact that it's evaporating very carefully. I can dis they discovered that, oh, it looks like actually I am able to represent some of the interior of the black hole in terms of this outside quantum description, which we hadn't seen before. Really. [00:40:00] And this led others to be able to write down more concretely, uh, The Hawking's original calculation of, of black hole evaporation, um, by finding other, let's say other terms that were not easy to see, but are now apparent when you look at things through this, this cool new lens, um, that helped to sort of resolve that information paradox.

Hmm. Deep

Sebastian Hassinger: it really interesting. So, so, okay. I mean the, the, the thing they refer to as hair, as sort of the, the information sort of, uh, um, uh, being preserved holographically on the outside of the black hole. Is that, is that right?

Grant Salton: I guess, yeah. I mean, um, people, people have different term, uh, uh, different meanings when they talk about black hole hair, so Yeah.

But, but I think what you're, yeah, I mean, what you're saying right, is that Yeah, indeed, right? That there's a, like black holes were one of the first, uh, the first things that people used to describe, um, a holographic system where they were saying like, I guess back in the seventies, [00:41:00] early seventies, maybe 72 or something, um, back instein.

Pointed out that the entropy of the black hole is scales as the area, the surface area of the black hole. You know, you got this big large region of space time and I can fill it with as much stuff as I want. And nevertheless, the entropy, which kind of describes how much information is in it, scales with the, with the, just the surface area.

And that, that was suggesting that the, the inside of this is dual to just the boundary. And that was one of these like sort of the earlier just, uh, evidences that maybe there are systems that have a holographic description.

Kevin Rowney: Oh, interesting. So that you, that was one of the first observations that kicked off this whole, this whole

Grant Salton: trial.

Yeah, it's one, one of the first ones. And, and this and this, uh, you know, this, um, claim that the entropy, this measure of information content or something to some extent depends on just the area of the black hole. That's very, that, that manifests very clearly in this a Ds safety correspondence. And, and so there you can kind of vary.[00:42:00]

Very naturally describe or, or represent the fact that this black hole has an entry that looks like just a boundary that that comes out from some of the recent results or the more recent results, I guess like two six. There was one that you can use to describe this. It's very, it's very nice to see that some of the early work, uh, has a, a much clearer description models

Sebastian Hassinger: and, and so, okay.

So there, there's clearly value in this quantum information experimentation for our understanding of, of the universe. I is there, is there the, the, the sort of the direction in the o you know, the other direction sort of learning where, where understanding black holes or worm holes or holographic universes can help us with things like quantum America, actually.

Cause I've, I've heard those two things, sort of that, that connection being made too.

Grant Salton: That that's one of the big hopes, um, of the, the from movement is that actually this is a two-way street. Um, right. There's been a lot of, I think there's been, I mean, just my, my own. Guess, and I, I've sort of [00:43:00] lost touch a little bit, but that is that most of the, most of the results do go in the one way of saying, here are some, here's some new insights into the a cft gravitational high energy physics, uh, problems that people think about when you phrase it in terms of information theory.

And I, that's, you know, that I think that's, that was to be expected, at least to me anyway, because you're just using information theory as, as a tool, uh mm-hmm. as a way of describing these other systems. And that gives you other techniques that maybe you just hadn't realized before, which are natural in this language, this different way of, you know, this other math.

But, um, going the other direction and say, well, here is some something where, uh, gravity is taught us about quantum computing. That's a little bit of a harder ask, but there are, there's some examples, right? So, um, you mentioned, uh, that space time. Kind of looks like a quantum error correcting code. And that was, you know, that was one of another one of these crowning achievements of this collaboration.

Is that, that indeed, that seems to be true in, in these, um, holographic quantum [00:44:00] systems. Thelen, Lenny Suskin likes to say this, right? That the, the hooks that bind the space time together is entanglement. And in particular, the structure that entanglement we're discovering is a quantum error correcting code.

And so by trying to figure out what that quantum error correcting code is, that that represents the, the space time in terms of the boundary, um, that gave us these new holographic quantum error correcting codes, uh, and some of the sensor network tools used to describe them. So that was sort of a new, uh, a, a new approach.

And we can use those four. And, which,

Sebastian Hassinger: I mean, is there specific codes that, that were informed? By that, I mean, is that, is that the, you know, the, like the, the surface codes? Is it the, um, which, which sort of family of, of error correcting codes are. Or, or influenced

Grant Salton: by that? The ones I have in mind, I mean, they're, people tend to reference them, refer to them as, as holographic codes.

They're sort of these, um, they kind of look like concatenated codes where you start with this, a quantum correction code, and then you sort of like [00:45:00] recursively encode each one of those little things out and further on, further on and sort of proliferates out. Uh, the reason for this is because you kind of, as you, um, it turns out that in this, in the, on the gravity side, if you want to represent something that's, that's really far into the space time, that's nowhere near like, you know, deep in the center of the can, that requires a description that's sort of, that uses most of the metal around it.

Hmm. If you wanna represent stuff that's very close to the can inside the, you know, like a piece of soup that's very close to the can, you only need to really think about the par of metal that's very close to it. Mm-hmm. . Mm-hmm. . And so there's, there's this, this notion that you have to kind of, the further in you go, the more encoded it has to be.

And this is where you get these kind of recursive codes coming out. So

Kevin Rowney: interesting. It's been a gigantic year, this pa this past year on quantum error correction. Numerous big, big results hitting. I mean, what do you think? Do you, uh, is it your, um, I don't know, thesis that this holographic thread of research could be, uh, even bigger news than what's happened this, this past year?

Grant Salton: Uh, I, I [00:46:00] don't know that it'll be bigger news, right? I think the stuff that's happening this year is there's some really important results and I, I think the, the work that the folks are doing on, on making Quantum America correction, actually, you know, getting to the point where it's going to start

Kevin Rowney: giving us, yeah, think it's over the threshold of, of recoverable error.

Yeah. That's, that's crucial. I think ,

Grant Salton: I think we need more of this. That's some more of those folks. The holographic stuff I think is nice. Uh, finding applications of this, um, That's that, you know, that that's something that I still think we need to do. Right. And for, for myself, my own, you know, coming back to the very beginning Right.

You're asking my, my journey into what I'm doing now. Right? Like I was working on this holographic stuff and, and, uh, quantum correction, these, these quantum correcting codes for space time and things like that. And I was trying to find ways of make it, making it a bit more practical or like Sure. Use new near term devices to, to like, to simulate these and, and, and trying to make things a bit more, more tangible.

And I think that, I think that needs to, to happen, right? [00:47:00] That we, I think that would be really exciting if we were able to take some, some of the findings from this mm-hmm. this, um, umbrella of ideas and say, ah, this is really cool. And look, it has this practical applic. Right.

Sebastian Hassinger: Well, I mean, especially the way that you described, um, the Google and Caltech teams working with ML to reduce the complexity of the circuit to, for this experiment, I, I just wonder like, you know, that's the problem with a lot of the, uh, the sort of, uh, theory around error correcting codes is it's extremely hard to implement on the machines that we have today.

Yeah. So I just wonder if there's a similar kinda effort that could go into, you know, finding simpler, uh, implementations of this, of all this math .

Grant Salton: Yeah. Yeah. Well, I guess, um, one of the upsides is that I'd say it feels like there's a lot more work happening in, in tensor networks these days. Mm-hmm. , and this is a, this, you know, this is a, a way of representing quantum systems that, that can maybe be more efficient or something like this.

And by virtue of being [00:48:00] exposed to them, Some of these results, like this holographic quantum americ correction, stuff like that. We've got more, we've got sort of, there's more people that are familiar with these techniques than were in the past. Uh, I would say, and it's a very broad, widely applicable way of, of thinking about quantum systems.

And the, it has the benefit of also being something that you could just simulate classically in a, in efficient ways. Mm-hmm. Some of the more efficient simulations of complicated quantum systems use these tensor network methods. Right. And indeed, I'd say Al already, I, I can think of a couple examples where people who have become, let's say, experts in tensor networks have been able, been able to say, ah, cool, now I can solve a problem that people actually care about in the real world, using these methods more efficiently.

Um, even if it's not really quantum just yet, but it's like, you know, it's, it's bridging connections between different things and that's always a good.

Kevin Rowney: Because there's tons, tons of machine learning and, and data science that depend upon, uh, tensor calculations. So yeah, there's a huge amount of, and is it

Sebastian Hassinger: the frontier there, sparseness [00:49:00] of the tensor network or is that, is that what, like if you can trim it, it down to sort of the minimal, uh, entanglement required for.

The problem then, then that makes it more attractable by classical simulation. Is

Grant Salton: that right? That's a, I think that's a, that's a good way of putting, I mean, there are other reasons why this would be the case, but yes, in gen in general, like if you have something that where you, where has a lot of structure and the, the way the entanglement spreads is sort of in.

Is itself also quite structured, then you can do a pretty, you can do a much more efficient simulation of this, this, these, the scrambling circuits, the, this real scrambling that you need to generate this hurricane and these wormhole papers mm-hmm. that has information spreading, uh, through entanglement as quickly as possible.

And so they're, yeah. The point is that it gets really hard to simulate that, uh, uh, really quickly, and this is why it, it's a really quantum, chaotic

Sebastian Hassinger: scenario. Interesting. Wow. Do you think there might be a path towards using this wormhole simulation experiment, um, [00:50:00] in, as a sort of next, uh, next generation supremacy test?

Like a benchmarking test? Like, uh, you know, using it to prove that a piece of hardware can do something that, that's, uh, intractable classically, I mean,

Grant Salton: I guess you would need. You would need much larger system sizes to be able to get some of these, right? Like the challenge with, with these sup supremacy results is that you need to be able to find something that you can do where you can tease out a signal, right.

And still get your answer despite all the noise. Um, yeah. And here in the, in these wormhole things, you're already looking for a signal, not just, so you don't necessarily get to maximize the signal. Like you don't get to choose which signal is going to be the strongest one that you can pull out. Mm-hmm.

there's one that you have to look for. Um, yeah. And so in that sense, maybe like, I would, I would love if this, if this turns out to be the case, I think that'd be super fun. Um mm-hmm. , if, if these ideas could be used to demonstrate. The real power of quantum computers, right. When we [00:51:00] couldn't do a classic. I think that'd be super fun.

Um, right.

Sebastian Hassinger: I think that's one of those, the way you described that the entanglement is achieved as quickly as possible. That's, that sounds like, you know, uh, it's, it's relying on the capability and the performance that are intrinsically quantum in nature, and therefore, you know, intuitively it sounds like something that would be pretty har easy to find the boundaries of what you could simulate classically.

Yeah,

Grant Salton: but the, on the other hand, right, so some of the early demonstrations of, of supremacy were themselves implementations of random quantum circuits. And a random circuit will, will sort of scramble information. But to do that as quickly as possible, you want this, the random circuit to be able to sort of couple qubits that are on, let's say different sides of the chips as easily as the ones that are nearest neighbors.

Yeah. And if your architecture only allows, you know, interactions close by. Yes. Right. You have to, you have to work around that. And so, um, to really. Scramble as strongly as, as you might need for some of these experiments, you might need longer circuit depths. Uh,

Sebastian Hassinger: interesting. Which might require better. Yeah, and I mean, that's what [00:52:00] I'm kind of thinking, you know, I mean even, you know, there's the recent paper that sort of create or, or, or put forward a theoretical proof of the, uh, the, the limitations of the, of the Google Random Circuit sampling, uh, experiment.

Um, showing that basically the, the, the, the larger the system that the more, the more quickly the, the simulation breaks down and the, and the weaker the supremacy claim, right. Um, at, at this level of noise essentially, which is, you know, that's to be expected. I'm just wondering if there may be some, uh, merit to.

Um, this, you know, scrambling circuit, uh, as a benchmark for, for like NextGen hardware that's hopefully less noisy and more capable .

Grant Salton: Yeah. Yeah. If you could, if you could do this, uh, if, if you could really implement these, these sort of all to all or, or long range right gates, um,

Sebastian Hassinger: or just super high gate rate.

Like, I mean, in superconducting cub you tend to have, you know, na nearest neighbor and if [00:53:00] you like, heavy hex, for example, in the IBM cases, it's not all to all, but you affect that, uh, you know, entanglement at, at a distance, let's say by, by a whole bunch of swaps, right? Right. So if the performance is, you know, high fidelity enough and fast enough, you'd be able to do that, that maximum entanglement or near maximum, you said it wasn't maximum maximum, but, uh, uh, the, the, the scrambling circuit, uh, um, function, uh, efficiently on, on a fast enough and high fidelity enough, uh, computer

Grant Salton: quantum computer.

Yeah. No, that's interesting. That's very true. Yes. Uh, it, it, you know, the, the longer, the larger the system, the more swaps you need and so you really need to like it. It's a good test. It becomes a much more demanding thing. Exactly. That's right. It's, it's testing your ability to control like different qubits and the, the gate fidelity and the coherence times all need to be good.

So the, the better the larger the system you want to do the, the harder becomes in in a few dimensions and I think so for that reason. Yeah. Could be [00:54:00] a very strong and,

Kevin Rowney: and all, all very contemporary engineering problems, they, they still are. That's right. Absolutely. Exactly. Hey, I, I just gotta reflect on this conversation because I, I had a grand time going through this material.

Thank you so much, grant, for your, your contribution here. Absolutely. I mean, just, just reflect on it. This is a almost a multi-course meal of like really rich, fun extraction, huh? Soup. Lots of, I mean, we had, we had medical isomorphism and anti sitter spaces, relativity, quantum information science, chaos theory, ml, quantum correction.

I mean, it just goes on and on. 10 network entanglement, the whole, I mean, geez, that's as about as good as it gets if , if you're into that dirt thing. buzz. Word tingle here. Yeah, exactly. Yeah. ,

Sebastian Hassinger: what do you, I mean, if you look forward, like what do you think are sort of the big, uh, if any challenges that are identified by the, the, from qubit crowd?

Is there something else that people are sort of shooting for as a result or,

Grant Salton: um, I want, yeah, I mean there was a lot of [00:55:00] work. There has been, there's sort of a lot of work on really understanding in detail this sort of information paradox, um, let's say resolution. Yeah. Uh, you know, it, it led to a lot of, um, deep insights into how information.

Can be recovered in the quantum systems and, and trying to understand that in depth, took people sort of to, you know, that that became a whole new sort of dimension of research. Um, I think a lot of people are trying to understand, all right, well we've got this great toy model of a DS cft. Mm-hmm. A DS is anti dissenter space, but we live in decision space.

So how, how, you know, what, what do we do here? Um, how do we make this a bit more realistic for ourselves? And there's, so there's been, there, there are efforts to try to understand how to, let's, or, or to understand whether or not we could have a toy model similar to this that's more akin to our own current reality or to understand, uh, the dynamics of flat space, what's also sort of like, you know, a good, a [00:56:00] reasonable approximation even if our full universe does not look like this right now.

And, um, so I think those kinds of questions, how to push this on the gravity side, how to push this into a realm that's not a toy model, that, that, uh, is very fruitful, but. But nevertheless, not correspond entire universe, but something that's maybe, uh, closer to us on the, on the quantum side, I think there's, there's still a desire, as you said, to try to get more mileage out of this kind of, this way of thinking.

Take other, the other tools and see if we, we can use them for, to learn something about quantum information theory, quantum error correction. Um, and then further than that, I think there's, depending on, depending on who you ask, there is still an appetite to also try to understand if these kinds of experiments, like, uh, like this one whole kind of thing, if we can use near term quantum devices.

We've got them, what are we gonna use them for right now? Right. Um, and the most likely thing is just, you know, experiments and understanding simulations of physics and, [00:57:00] you know, I think it's

Kevin Rowney: produce real results of significance for, for deep

Sebastian Hassinger: science. Yeah, yeah, yeah. Yeah. I keep making the same joke, but the, the com, the quantum computers we make today are kind of crappy computers and really exotic lab instruments.

Right. , there's all kinds of really interesting sciences being done in these devices. That's right. That's

Grant Salton: right. Yeah. And I think, I think there is still, there's a lot that we can learn on, on sort of both sides, right? Like, uh, as, as you were pointing out, we can learn, we learn what it would take to be able to run more, uh, more complicated physics experiments in terms of engineering.

How do we have to build these devices, right? To be able to, to simulate physics outside of the simpler things that we can do right now. And also, can we use them to understand new things that we hadn't yet discovered, um, about some of these physical systems that we're studying, uh, from a theory

Sebastian Hassinger: perspective.

That's fantastic. Well, we'll, uh, we'll keep you on speed dial for future hit from qubit results. Yeah. That, that

Kevin Rowney: was so really, really, yeah. Thank you. Please fun super [00:58:00]

Grant Salton: chat about this. You know, these days I think about more practical applications of quantum computer, so I love getting a chance to, to riff about this

Kevin Rowney: stuff.

Yeah.

Wow. I, that was, that was great fun. Sebastian. Uh, it was Grant. Grant really, uh, brought it on. I, I [00:59:00] mean, I gotta say it again. I mean that, that whole, uh, That menu of really rich, um, abstractions, you know, uh, mathematical isomorphism and anti hitter spaces, general relativity, wormholes, entanglement, I, you know, and, and machine learning results to somehow get to the right circuit of the quantum computer.

I mean, wow. That was a, a rich multi-course

Sebastian Hassinger: meal. It was . It really was. Yeah. Yeah. And I, I almost feel like we need another episode to sort of go through the glossary that you ran through . That's true. My god, like 10 minutes of context for each one. But yeah, it was really great. And you know, the reason that I'm so drawn to it from qubit is that it's, it's such a great example of these emerging.

Sci, I would call 'em scientific use cases where these devices that we're building today are enabling new science, new experimentation, not just validation of of claims, which is important in and of itself, as we were saying, but also breaking new ground on our understanding of the universe [01:00:00] itself, uh, which is.

Incredibly interesting and exciting. Um, and at the same time, the science is causing the, the engineering and the, and the technology to stretch in ways that are, are making it more likely that we'll find our way to devices that are actually useful, useful, fall tolerant, universal computers that are useful for, you know, industry commercial purposes.

Right. Yeah. So it's this fascinating. Often in, in, uh, physics, I've run across this term co-design and it, it's where experimentalists and theorists work together. Yes. And now we're seeing an expansion of co-design into engineering and technologists in a, a way that I think is, uh, incredibly exciting. . Yeah.

Really

Kevin Rowney: neat. Yeah. I, I, such a good time. I, I'm glad you found this guest. Absolutely,

Sebastian Hassinger: absolutely. . So that's it for this week's episode. Um, we apologize for the delay since the last, last episode. We're going to continue to try to get these out every couple weeks. There was a little bit longer [01:01:00] delay before this one, um, but, uh, we hope that to see you on the next episode as well.

Thank you.

Kevin Rowney: Awesome. Thanks. Okay. That's it for this episode of the New Quantum Era, a podcast by Sebastian Haer and Kevin Rooney. Our cool theme music was composed and played by Omar Costa Hao. Production work is done by our wonderful team over at Pod five. If you are at all like us and enjoy this rich, deep and interesting topic, please subscribe to our podcast on whichever platform you may stream from.

Un even consider if you like what you've heard today reviewing us on iTunes and or mentioning us on your preferred social media platforms. We're just trying to get the word out on this fascinating topic and would really appreciate your help spreading the word and building community. Thank you so much for your time.