Quantum information theory sheds light on quantum gravity

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Hello, and welcome to the first Physics World

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weekly podcast of 2026.

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I'm Hamish Johnston.

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In this episode, I'm in conversation with Alex

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May,

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who is the Murray Gautman

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Chair in Theoretical Physics

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at the Perimeter Institute

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in Waterloo, Canada.

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Much of Alex's research

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explores how quantum information theory can help us

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solve

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one of the most enduring

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mysteries in physics.

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How to reconcile

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quantum mechanics

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with Einstein's

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general theory of relativity

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to create a viable theory of quantum gravity.

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Our conversation is coming up after this message

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of support

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from the APS

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Global Physics Summit,

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which takes place on March

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2026

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in Denver, Colorado,

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and online.

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At the largest physics meeting in the world,

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you can join thousands of physicists,

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and collaboration.

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Immerse yourself

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in the cutting edge science that's shaping our

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shared future,

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and be part of the global

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physics community

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forward.

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Explore the meeting at summit.aps.org.

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I'm at the Perimeter Institute in Waterloo, Ontario,

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and I'm very pleased to be joined by

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Alex May.

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Hi, Alex. Welcome to the podcast.

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Hey, Hamish. How are you doing? I'm fine.

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Thanks. And I'm very excited to chat with

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you about the intersection between quantum information theory

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and quantum gravity.

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So can we start off maybe with a

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few definitions?

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What is quantum information

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theory? Can you give us a a simple

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take on it if possible?

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Yeah. So,

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there's lots of context we're familiar with where

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we're interested in

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doing what we might call information processing.

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So when you,

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run a program on your computer, you're processing

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information in some way. When I send you

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a message over the Internet or over the

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phone,

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we are,

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yeah, again, processing information in a different way.

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In that case, we're communicating instead of computing.

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There's other aspects about, you know, how you

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keep information secure,

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so that's called cryptography.

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And

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what quantum information theory is, is you're taking

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the properties of quantum mechanics,

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all the things that are weird and and

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cool about it, and seeing how it changes

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what you can do when it comes to

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information processing. So how how does the strangeness

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of quantum mechanics

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help us compute better, help us open up

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new possibilities in how we communicate, in how

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we keep information secure, and and so on.

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I see. And and it can be very

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useful, can't it?

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Quantum well, the the quantum mechanics,

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itself,

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there are some benefits to to using it

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in a in an information

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paradigm, isn't there? Yeah. That's right. So the

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most famous example is with quantum computing.

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So there's lots of excitement about that.

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There are certain problems that,

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our understanding is that using,

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computers based on the principles of quantum mechanics,

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we can solve them quickly,

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even while

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a traditional computer, what's called a classical computer,

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would really struggle. It would take a long,

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long time. There's lots of other ways that

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we can get advantages out of using quantum

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mechanics, though, beyond computing, which is maybe what

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you hear about the most.

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So,

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another subject is what's called quantum key distribution.

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So that's where using properties of quantum mechanics

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to let you,

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communicate securely in a way that's that's not

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possible otherwise.

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I see. Right.

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And, Alex, you know, sort of,

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when you look at it, you know, maybe

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naively, that seems like a million miles away

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from quantum gravity,

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which,

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you know, it I mean, seems to be

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a very

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sort of esoteric

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field.

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And I I just wanted to to get

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started with quantum gravity by asking you,

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why why don't we have a a good

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understanding

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or theory of quantum gravity? What what is

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the what are the challenges

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that you and other physicists are encountering when

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you're trying to develop theories?

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Yeah. So I think I think there's lots

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of ways of understanding what goes wrong with

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our usual approach to to understanding, you know,

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a quantum theory with that

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or what goes wrong when you deal with

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gravity in particular.

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So one

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one way to understand this is in the

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language of field theory. So

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in quantum field theories,

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field theories are sort of come in two

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types. So there's renormalizable ones and nonrenormalizable

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ones.

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And,

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maybe without specifying exactly what that means,

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the the high the high level picture is

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that a renormalizable

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theory

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kind of makes sense at all energies. K.

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So it makes sense. We can make low

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energy predictions, but it continues to make sense

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at high energy.

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The theory might not be experimentally correct at

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high energy, but the theory itself is not

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telling you that there's something wrong at high

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energy.

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A non renormalizable

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theory,

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it's the other way. So it's

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it knows that something is wrong with it

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at high energies. You try and make a

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prediction of high energy, it gives you infinity,

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something something goes wrong.

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So

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gravity,

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you know, we have a theory of gravity.

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We have Einstein's general relativity.

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You can cast that as a as a

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field theory,

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as a quantum field theory, and it makes

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sense at lower energies.

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Right? So you can do,

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you know, the kind of physics relevant

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to maybe planets orbiting around stars or something

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like that using general relativity or or in

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this field theory framework, and and everything's okay.

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But

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the

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the fact that this theory is nonrenormalizable

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is telling you that if you try and

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use this at very high energy scales, if

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you try and use our understanding of gravity

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at high at high energies,

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things go wrong. Okay.

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That by itself is not so bad. Right?

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So there's lots of other field theories that

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had been written written down that were nonrenormalizable

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that we later figured out,

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you know, were just some other more detailed

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field theory at at high energies. So you

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can write down a field theory that describes

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neutrons,

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and it's not were normalizable.

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It's telling you that above some energy scale,

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there's some new physics that this theory doesn't

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know about.

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The new physics isn't that wild. It's just

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saying that, oh, actually, neutrons are made out

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of some

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constituent particles, and if you go to high

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energies, you're gonna see that. So your original

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theory didn't see that didn't didn't know about

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those particles. Right?

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We actually know that with gravity,

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the solution is not

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as simple as that. So there's a theorem

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called the Weinberg Witten theorem

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tells you that the graviton, like the basic

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excitation in your theory of gravity

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is not,

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it's not just some composite particle. It's not

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gonna break apart when you go up to

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go to high energies.

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That's not where the new physics is coming

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from.

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So instead, there has to be some

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more exotic,

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new physics that happens at high energies,

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and the challenge is in identifying what that

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is.

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I see. And and in your research,

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a a lot of your research focuses on

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non local

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quantum computation,

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I suppose, as applied to quantum gravity.

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What is NLQC,

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and why is it important

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to, study? Why are you interested in it?

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Yeah. Okay. So

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maybe we can we can sort of continue

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with with the story of that I was

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trying to describe in the last question where,

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you know, we know that there's some,

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maybe sort of exotic new physics coming in

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at

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that's relevant to high energies.

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One possibility that's been identified for a long

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time

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is,

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goes goes by the name of the holographic

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principle.

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Okay. And so this is this is the

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claim,

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that

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the reason this theory of gravity isn't working

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at high energies is that,

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or at least the way to get around

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this is to

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give some alternative description of gravity

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in one less dimension than we would usually

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think it would live in. So we live

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in a three plus one dimensional

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space,

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and the holographic principle suggests that there's some

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just two plus one dimensional description

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of this world. Okay? Or, you know, four

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dimensional gravity is described in terms of some

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three-dimensional

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non gravitating, just quantum mechanical theory.

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So this this sounds a little bit crazy.

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It's saying that we kind of live in

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some lower dimensional hologram,

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but it's well motivated. You know, one way

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to motivate it is from this kind of

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Weinberg Witten description or picture that I was

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that I was describing, but another comes from

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the physics of black holes. So

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with a black hole,

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we've identified that the entropy of the black

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hole seems to be given by the area

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of the hole.

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And so this is somehow saying that the

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amount of information in the black hole, the

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number of degrees of freedom,

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is

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not like the volume, like you would expect

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for an ordinary,

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an ordinary system, but somehow,

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there's fewer degrees of freedom and there's only

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an area's worth. Okay.

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And we think that not just black holes,

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but actually,

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everything sort of works like that. So, you

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know, we think we have sort

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of three dimensions worth of degrees of freedom,

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but,

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apparently, there's there's this lower dimensional description in

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terms of just

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two dimensions worth of degrees of freedom.

283
00:10:16,769 --> 00:10:19,009
Okay. So that that's part of the exotic

284
00:10:19,009 --> 00:10:20,610
physics that seems to take over at at

285
00:10:20,610 --> 00:10:22,449
high energies when you're trying to do quantum

286
00:10:22,449 --> 00:10:22,949
gravity.

287
00:10:24,929 --> 00:10:25,429
So

288
00:10:25,970 --> 00:10:26,949
okay. So

289
00:10:27,730 --> 00:10:28,049
now,

290
00:10:29,495 --> 00:10:32,235
what is the subject of nonlocal quantum computation,

291
00:10:32,294 --> 00:10:33,995
and and how is it related here?

292
00:10:35,254 --> 00:10:36,875
Well, to get to that,

293
00:10:37,735 --> 00:10:38,235
let's

294
00:10:38,695 --> 00:10:40,535
go to a very different setting for a

295
00:10:40,535 --> 00:10:42,934
second. So this is a setting in quantum

296
00:10:42,934 --> 00:10:43,914
information theory.

297
00:10:45,179 --> 00:10:47,439
In particular, it's a setting in,

298
00:10:47,740 --> 00:10:48,480
in cryptography.

299
00:10:49,500 --> 00:10:50,000
K?

300
00:10:50,459 --> 00:10:52,159
So cryptography is all about,

301
00:10:53,179 --> 00:10:55,120
establishing trust, keeping secrets,

302
00:10:55,500 --> 00:10:58,079
processing information securely, so on.

303
00:10:58,695 --> 00:10:59,175
And,

304
00:10:59,495 --> 00:11:01,095
one thing that you could be interested in

305
00:11:01,095 --> 00:11:02,394
doing in that context

306
00:11:03,095 --> 00:11:03,595
is,

307
00:11:04,134 --> 00:11:05,035
is in checking

308
00:11:05,415 --> 00:11:08,774
where physically in space somebody is. So you're

309
00:11:08,774 --> 00:11:10,455
talking to somebody, you're talking to them over

310
00:11:10,455 --> 00:11:11,274
the phone, say,

311
00:11:12,200 --> 00:11:13,960
but you wanna know that the person you're

312
00:11:13,960 --> 00:11:15,980
talking to is located in a certain spot.

313
00:11:16,279 --> 00:11:16,779
Right?

314
00:11:17,320 --> 00:11:18,600
You might wanna do that as a way

315
00:11:18,600 --> 00:11:20,840
of establishing trust. Right? We often trust people

316
00:11:20,840 --> 00:11:22,440
based on where they are. You know, you

317
00:11:22,440 --> 00:11:23,259
go to the bank,

318
00:11:23,985 --> 00:11:25,664
you go to the person behind the till,

319
00:11:25,664 --> 00:11:27,024
you take out your wallet, you give them

320
00:11:27,024 --> 00:11:29,105
your money, your information. You've never met this

321
00:11:29,105 --> 00:11:31,264
person. You didn't check their ID. You trust

322
00:11:31,264 --> 00:11:33,745
them because they're behind the till. Right? So

323
00:11:33,745 --> 00:11:35,345
you might use location as a sort of

324
00:11:35,345 --> 00:11:36,804
proxy for for trust.

325
00:11:38,464 --> 00:11:38,705
So

326
00:11:39,959 --> 00:11:40,459
okay.

327
00:11:41,000 --> 00:11:43,480
So starting with that idea, there's this subject

328
00:11:43,480 --> 00:11:44,459
in quantum cryptography

329
00:11:44,839 --> 00:11:45,339
around

330
00:11:46,120 --> 00:11:47,980
trying to check where somebody is.

331
00:11:48,759 --> 00:11:51,179
And what was realized by the cryptographers

332
00:11:51,815 --> 00:11:53,735
is that you could use this technique, which

333
00:11:53,735 --> 00:11:55,514
is this non local quantum computation,

334
00:11:56,454 --> 00:11:59,674
to always allow somebody to cheat in this,

335
00:12:00,214 --> 00:12:01,815
in this kind of scenario where you're trying

336
00:12:01,815 --> 00:12:03,834
to check where they are. And in particular,

337
00:12:04,134 --> 00:12:05,514
what they realized is

338
00:12:05,860 --> 00:12:06,360
if

339
00:12:06,820 --> 00:12:09,320
you think you're interacting with somebody sort of

340
00:12:09,379 --> 00:12:10,600
inside of some volume,

341
00:12:12,500 --> 00:12:15,299
the responses that that person gives you, right,

342
00:12:15,299 --> 00:12:16,660
I give you some inputs, they give you

343
00:12:16,660 --> 00:12:17,320
some outputs,

344
00:12:18,164 --> 00:12:20,884
Those responses can always be simulated by somebody

345
00:12:20,884 --> 00:12:22,424
who's hanging out near the boundary

346
00:12:23,284 --> 00:12:23,684
of,

347
00:12:24,644 --> 00:12:26,664
of that volume where you're supposed to be.

348
00:12:27,605 --> 00:12:31,000
So that's unfortunate for the for the for

349
00:12:31,000 --> 00:12:33,100
the cryptographic goal. Right? It's saying that there's,

350
00:12:33,480 --> 00:12:35,079
at least in a in a very general

351
00:12:35,079 --> 00:12:36,220
context, no way

352
00:12:37,079 --> 00:12:39,079
to to be sure about where the person

353
00:12:39,079 --> 00:12:40,220
you're talking to is,

354
00:12:40,600 --> 00:12:41,980
but it has this very

355
00:12:42,679 --> 00:12:44,459
interesting connection to this

356
00:12:45,274 --> 00:12:48,154
this holography idea from point of gravity, and

357
00:12:48,154 --> 00:12:49,054
that it's saying,

358
00:12:49,674 --> 00:12:52,414
you know, anything happening in this volume

359
00:12:53,035 --> 00:12:55,375
can be replaced by something happening

360
00:12:55,914 --> 00:12:57,375
at the boundary of that volume.

361
00:12:58,100 --> 00:12:59,940
And that sounds a lot like calligraphy where

362
00:12:59,940 --> 00:13:02,360
it's saying, oh, there's a three-dimensional script description,

363
00:13:02,659 --> 00:13:04,980
but there's some alternative, you know, two dimensional

364
00:13:04,980 --> 00:13:06,839
description or lower dimensional description.

365
00:13:09,299 --> 00:13:11,320
So, yeah, that's kind of the starting point.

366
00:13:11,699 --> 00:13:12,440
There's some

367
00:13:13,075 --> 00:13:14,774
similarity between these subjects.

368
00:13:15,554 --> 00:13:16,214
And then,

369
00:13:16,754 --> 00:13:18,355
you can start trying to make this connection

370
00:13:18,355 --> 00:13:18,855
precise.

371
00:13:20,115 --> 00:13:22,615
And, to do that, you need some precise,

372
00:13:23,875 --> 00:13:25,254
theory of quantum gravity.

373
00:13:26,309 --> 00:13:26,789
And,

374
00:13:27,350 --> 00:13:29,029
the way that that's the context in which

375
00:13:29,029 --> 00:13:30,389
this has all been made most precise is

376
00:13:30,389 --> 00:13:32,089
something called the AdS CFT correspondence.

377
00:13:33,350 --> 00:13:35,509
And there, we find that, you know, these

378
00:13:35,509 --> 00:13:37,529
results that cryptographers had proven

379
00:13:37,884 --> 00:13:38,704
years ago

380
00:13:39,245 --> 00:13:41,824
about nonlocal computation lead to very precise

381
00:13:42,284 --> 00:13:45,245
and new statements about gravity and ADS space

382
00:13:45,245 --> 00:13:48,384
times, and that's quite a, a surprising connection.

383
00:13:49,004 --> 00:13:50,865
I see. And and so

384
00:13:51,324 --> 00:13:53,959
how how do you so you've got this

385
00:13:53,959 --> 00:13:56,440
correspondence. You can show I'm guessing you can

386
00:13:56,440 --> 00:13:57,259
show mathematically

387
00:13:58,039 --> 00:14:01,419
that it's that there's a strong correspondence between

388
00:14:01,879 --> 00:14:02,700
these two,

389
00:14:03,720 --> 00:14:06,299
well, that sound very, very different Yeah.

390
00:14:06,839 --> 00:14:07,339
Concepts.

391
00:14:07,835 --> 00:14:10,014
How how does that help you

392
00:14:10,715 --> 00:14:11,855
come up with a theory

393
00:14:12,394 --> 00:14:16,235
of quantum gravity? Does that is that are

394
00:14:16,235 --> 00:14:17,695
these like building blocks

395
00:14:18,075 --> 00:14:19,134
that you can use?

396
00:14:19,595 --> 00:14:20,575
Yeah. So AdSCFT

397
00:14:20,955 --> 00:14:23,210
is, I mean, we can't prove it mathematically.

398
00:14:23,210 --> 00:14:25,370
It's a conjecture. There's lots of evidence for

399
00:14:25,370 --> 00:14:27,210
it. We can we can check many aspects

400
00:14:27,210 --> 00:14:28,750
of it, and it seems to work out.

401
00:14:29,610 --> 00:14:31,050
But well, maybe I should say first of

402
00:14:31,050 --> 00:14:32,490
all what it is. It's it's a claim

403
00:14:32,490 --> 00:14:32,990
that

404
00:14:33,924 --> 00:14:36,325
two very apparently very different looking theories are

405
00:14:36,325 --> 00:14:36,825
actually

406
00:14:37,205 --> 00:14:37,705
equivalent.

407
00:14:39,684 --> 00:14:42,085
So the two theories would be, a higher

408
00:14:42,085 --> 00:14:45,205
dimensional gravitating theory and then a lower dimensional

409
00:14:45,205 --> 00:14:47,465
just quantum mechanical theory, like like the holographic

410
00:14:47,524 --> 00:14:49,019
principle says we should have.

411
00:14:51,980 --> 00:14:52,480
It's

412
00:14:53,179 --> 00:14:55,899
within a certain context. So this doesn't apply

413
00:14:55,899 --> 00:14:59,660
to all theories of gravity. Right? It applies

414
00:14:59,660 --> 00:15:01,500
to theories of gravity that live in a

415
00:15:01,500 --> 00:15:03,259
special kind of a space time called the

416
00:15:03,259 --> 00:15:03,759
asymptotically

417
00:15:04,139 --> 00:15:05,625
ADF space. K.

418
00:15:06,085 --> 00:15:06,585
That's

419
00:15:07,205 --> 00:15:09,205
it's a little unfortunate that it only applies

420
00:15:09,205 --> 00:15:10,585
to that kind of space time,

421
00:15:12,165 --> 00:15:14,404
in that we don't think that we actually

422
00:15:14,404 --> 00:15:17,524
live in an asymptotically ADS space. We live

423
00:15:17,524 --> 00:15:18,245
in a,

424
00:15:19,045 --> 00:15:20,759
somewhat different looking space time.

425
00:15:21,399 --> 00:15:23,639
But, you know, nonetheless, this is some kind

426
00:15:23,639 --> 00:15:26,279
of working, at least toy model of quantum

427
00:15:26,279 --> 00:15:29,639
gravity. It's saying, here's this gravitational physics. It's

428
00:15:29,639 --> 00:15:32,700
recorded into just some quantum mechanical physics,

429
00:15:33,884 --> 00:15:35,964
and it's up to us to study how

430
00:15:35,964 --> 00:15:37,504
these things fit into each other,

431
00:15:38,125 --> 00:15:40,544
try and extract the key ideas there,

432
00:15:40,924 --> 00:15:42,464
and then from that,

433
00:15:43,245 --> 00:15:45,485
hopefully go and use those ideas to describe,

434
00:15:45,485 --> 00:15:47,904
you know, quantum gravity in the actual universe.

435
00:15:48,284 --> 00:15:51,289
I see. And the the this quantum cryptography

436
00:15:51,589 --> 00:15:52,730
system, does that,

437
00:15:53,750 --> 00:15:55,029
I mean, does that give you,

438
00:15:56,149 --> 00:15:57,129
an analog

439
00:15:57,509 --> 00:15:58,490
that you can,

440
00:15:58,950 --> 00:16:01,429
I don't know, manipulate and probe or, I

441
00:16:01,429 --> 00:16:02,730
mean, even do experiments

442
00:16:03,065 --> 00:16:05,245
in the lab that could inform

443
00:16:06,184 --> 00:16:08,605
your your understanding of quantum gravity?

444
00:16:09,304 --> 00:16:09,804
Yeah.

445
00:16:10,825 --> 00:16:12,605
I I would say, like, in

446
00:16:13,784 --> 00:16:15,910
in a certain sense, it's it's

447
00:16:16,290 --> 00:16:19,170
a totally quantum mechanical analog of of at

448
00:16:19,170 --> 00:16:21,330
least one aspect of what happens in ADS

449
00:16:21,330 --> 00:16:21,830
CFT.

450
00:16:22,210 --> 00:16:24,529
It's not like a full model or something

451
00:16:24,529 --> 00:16:25,490
like that, but I think it,

452
00:16:27,424 --> 00:16:30,544
it explains and captures, like, one aspect of

453
00:16:30,544 --> 00:16:31,924
the physics in ADS CFT.

454
00:16:34,464 --> 00:16:37,044
That, like, so far has just been used

455
00:16:38,384 --> 00:16:40,884
at the level of, like, here's some mathematical

456
00:16:41,024 --> 00:16:44,089
result around nonlocal computation, and then

457
00:16:44,710 --> 00:16:46,490
here's how we apply it to ADSCFT.

458
00:16:47,830 --> 00:16:50,070
And it leads to, you know, maybe some

459
00:16:50,070 --> 00:16:51,210
theorem about gravity,

460
00:16:51,589 --> 00:16:53,289
some precise consequence there.

461
00:16:54,549 --> 00:16:56,409
I think you could start thinking about

462
00:16:57,595 --> 00:16:59,995
things like, you know, how do I make

463
00:16:59,995 --> 00:17:00,975
a quantum system

464
00:17:01,754 --> 00:17:03,995
that is doing one of these nonlocal quantum

465
00:17:03,995 --> 00:17:04,494
computations

466
00:17:05,434 --> 00:17:06,794
and is doing it in a way that,

467
00:17:06,794 --> 00:17:09,294
like, looks more like a gravitating system?

468
00:17:09,994 --> 00:17:11,595
And then can I go and build that

469
00:17:11,595 --> 00:17:12,414
in my lab?

470
00:17:12,900 --> 00:17:13,400
And,

471
00:17:13,940 --> 00:17:16,119
yeah, that's a question that you could ask.

472
00:17:16,180 --> 00:17:17,400
I I guess I,

473
00:17:19,700 --> 00:17:20,600
I don't have

474
00:17:21,140 --> 00:17:22,279
a sharp question

475
00:17:23,940 --> 00:17:25,940
about ADS CFT that I want to try

476
00:17:25,940 --> 00:17:27,015
and answer that way,

477
00:17:28,055 --> 00:17:29,575
but I think it could be worth exploring.

478
00:17:29,575 --> 00:17:33,115
Yeah. I see. And before we started recording,

479
00:17:33,734 --> 00:17:35,815
we we were chatting a bit about the

480
00:17:35,815 --> 00:17:39,660
intersection of quantum gravity and quantum information. Yeah.

481
00:17:40,140 --> 00:17:41,980
I mean, I'm guessing that what we've just

482
00:17:41,980 --> 00:17:43,759
been talking about is probably

483
00:17:44,220 --> 00:17:46,700
just a small That's right. Aspect. Can can

484
00:17:46,700 --> 00:17:48,460
you talk a bit, you know, about the

485
00:17:48,460 --> 00:17:50,220
field in general? Is this sort of a

486
00:17:50,220 --> 00:17:51,580
growing field that,

487
00:17:52,460 --> 00:17:55,519
theorists are becoming more and more interested in?

488
00:17:56,035 --> 00:17:58,595
Yeah. So definitely yeah. I should emphasize the

489
00:17:58,595 --> 00:18:00,434
the the thing I was describing is one

490
00:18:00,434 --> 00:18:02,855
one aspect of this broader,

491
00:18:03,234 --> 00:18:04,775
deeper connection between,

492
00:18:06,035 --> 00:18:08,595
quantum information theory and and quantum gravity and

493
00:18:08,595 --> 00:18:11,490
and especially the ADFCFT correspondence, but but even

494
00:18:11,490 --> 00:18:13,509
more broadly in quantum gravity than that.

495
00:18:16,210 --> 00:18:16,710
And,

496
00:18:17,329 --> 00:18:19,009
yeah, I think one one question I get

497
00:18:19,009 --> 00:18:19,990
a lot about,

498
00:18:21,170 --> 00:18:23,029
you know, these two fields is, like,

499
00:18:23,455 --> 00:18:25,475
why is there any connection at all?

500
00:18:26,975 --> 00:18:28,914
I think there's different ways to understand that.

501
00:18:29,535 --> 00:18:31,475
One way to understand it is just that,

502
00:18:32,815 --> 00:18:35,215
in a sense, quantum information theory, you know,

503
00:18:35,215 --> 00:18:37,049
was built up to answer the kind of

504
00:18:37,130 --> 00:18:39,049
somewhat practical questions that I was describing. How

505
00:18:39,049 --> 00:18:40,809
do we compute better? How do we communicate

506
00:18:40,809 --> 00:18:41,309
better?

507
00:18:41,930 --> 00:18:43,289
You know, this is about stuff we want

508
00:18:43,289 --> 00:18:44,910
to do, stuff we want to build.

509
00:18:45,769 --> 00:18:47,610
But when you try and answer those questions,

510
00:18:47,610 --> 00:18:48,890
one thing that you end up doing is

511
00:18:48,890 --> 00:18:51,049
just end up developing a whole new way

512
00:18:51,049 --> 00:18:52,430
to understand quantum mechanics.

513
00:18:53,345 --> 00:18:53,845
And,

514
00:18:55,345 --> 00:18:57,765
you know, powerful tools for for,

515
00:18:58,065 --> 00:19:00,305
you know, just understanding interesting properties of quantum

516
00:19:00,305 --> 00:19:01,285
mechanics. Right?

517
00:19:01,825 --> 00:19:03,825
And so much of the physics that we

518
00:19:03,825 --> 00:19:04,325
do,

519
00:19:04,865 --> 00:19:07,500
right, is in that quantum mechanic is in

520
00:19:07,500 --> 00:19:09,419
the framework of quantum mechanics. Most of physics

521
00:19:09,419 --> 00:19:10,779
is in the, you know, except for gravity

522
00:19:10,779 --> 00:19:12,220
at this point, in the framework of quantum

523
00:19:12,220 --> 00:19:12,720
mechanics.

524
00:19:13,579 --> 00:19:15,419
And and that opens up the possibility that

525
00:19:15,419 --> 00:19:17,740
these same tools that we use to understand

526
00:19:17,740 --> 00:19:19,119
these kind of practical questions,

527
00:19:20,085 --> 00:19:23,105
can be reused in other contexts, right? And

528
00:19:23,125 --> 00:19:26,085
quantum gravity is one context in which we're

529
00:19:26,085 --> 00:19:28,484
seeing that, but there's others too, right? Like

530
00:19:28,484 --> 00:19:30,904
in condensed matter physics, in quantum matter,

531
00:19:31,924 --> 00:19:33,065
we're also seeing,

532
00:19:34,005 --> 00:19:36,500
a lot of these tools from quantum information

533
00:19:36,720 --> 00:19:37,460
being applied,

534
00:19:38,400 --> 00:19:40,420
to to to understand those kind of systems.

535
00:19:41,039 --> 00:19:42,480
And and do you think I mean, has

536
00:19:42,480 --> 00:19:43,700
it, you know, the

537
00:19:44,080 --> 00:19:46,580
boom, well, for lack of a better word,

538
00:19:46,960 --> 00:19:47,860
in in

539
00:19:48,174 --> 00:19:50,654
quantum information research and, you know, the real

540
00:19:50,654 --> 00:19:52,815
depth of understanding that physicists are

541
00:19:53,454 --> 00:19:54,815
have developed. Is that,

542
00:19:55,934 --> 00:19:58,654
I mean, is that something that's, I suppose,

543
00:19:58,654 --> 00:20:00,414
moving outside? I mean, it sounds like it's

544
00:20:00,414 --> 00:20:03,214
moving outside of the quantum information community and

545
00:20:03,214 --> 00:20:03,714
benefiting,

546
00:20:04,390 --> 00:20:06,230
well, you know, people like yourself who are

547
00:20:06,230 --> 00:20:08,549
interested in gravity and people who are interested

548
00:20:08,549 --> 00:20:11,509
in lots of other different kinds of physics.

549
00:20:11,509 --> 00:20:13,190
I'm has it been a I mean, it

550
00:20:13,190 --> 00:20:14,970
sounds like it's been a really positive,

551
00:20:15,349 --> 00:20:17,429
or it's had a very positive impact on

552
00:20:17,429 --> 00:20:19,825
the physics community over the last, I don't

553
00:20:19,825 --> 00:20:22,225
know, twenty, twenty five years. Yeah. I I

554
00:20:22,225 --> 00:20:23,985
certainly think so, and it's certainly up something

555
00:20:23,985 --> 00:20:24,945
I'm excited about.

556
00:20:25,505 --> 00:20:26,805
You know, I think that

557
00:20:27,424 --> 00:20:29,045
to to me, it's a whole different

558
00:20:29,585 --> 00:20:32,099
starting point for understanding quantum mechanics. Like,

559
00:20:32,660 --> 00:20:35,000
when we teach quantum mechanics in undergrad,

560
00:20:36,099 --> 00:20:37,799
we teach it in the context,

561
00:20:38,179 --> 00:20:39,460
at least traditionally, we teach it in the

562
00:20:39,460 --> 00:20:41,140
context that it was developed, which is in

563
00:20:41,140 --> 00:20:43,319
the context of, like, atomic physics.

564
00:20:43,700 --> 00:20:45,859
But quantum mechanics is something much, much more

565
00:20:45,859 --> 00:20:47,799
general than atomic physics,

566
00:20:48,595 --> 00:20:49,095
And

567
00:20:49,875 --> 00:20:51,654
quantum information gives you,

568
00:20:52,115 --> 00:20:53,794
you know, a different lens, a different set

569
00:20:53,794 --> 00:20:56,434
of examples and starting points for thinking about

570
00:20:56,434 --> 00:20:57,255
quantum mechanics.

571
00:20:57,954 --> 00:20:58,434
And,

572
00:20:59,634 --> 00:21:01,554
it also gives you a lot simpler context

573
00:21:01,554 --> 00:21:02,294
for understanding

574
00:21:02,799 --> 00:21:04,339
quantum mechanics. Like I think that,

575
00:21:04,720 --> 00:21:06,400
you know, when you solve the hydrogen atom,

576
00:21:06,400 --> 00:21:08,420
that's an excellent thing that everybody should do.

577
00:21:10,320 --> 00:21:11,940
But if you just want to understand

578
00:21:12,720 --> 00:21:14,880
what are the core features of quantum mechanics

579
00:21:14,880 --> 00:21:16,799
that I need to conceptually get my head

580
00:21:16,799 --> 00:21:17,299
around

581
00:21:17,835 --> 00:21:20,634
something like the quantum teleportation protocol. Some of

582
00:21:20,634 --> 00:21:23,194
the basic aspects of quantum information theory can

583
00:21:23,194 --> 00:21:25,194
be a quicker route to to to getting

584
00:21:25,194 --> 00:21:26,815
that understanding, I think. So,

585
00:21:27,835 --> 00:21:29,194
yeah, it's just a really clean way to

586
00:21:29,194 --> 00:21:30,894
understand quantum mechanics, and that

587
00:21:31,549 --> 00:21:33,230
has this knock on effect of of,

588
00:21:33,630 --> 00:21:35,970
coming into all these other areas. I see.

589
00:21:36,190 --> 00:21:38,509
And, you know, just sort of thinking back

590
00:21:38,509 --> 00:21:41,230
to my education in physics, I mean, I'm

591
00:21:41,230 --> 00:21:43,009
guessing, you know, the last time I

592
00:21:43,390 --> 00:21:44,769
took a course in quantum

593
00:21:45,315 --> 00:21:47,494
mechanics would have been sometime in the nineties.

594
00:21:47,714 --> 00:21:49,554
And, you know, it was very much, you

595
00:21:49,554 --> 00:21:51,815
know, the simple harmonic oscillator.

596
00:21:52,194 --> 00:21:54,434
Yep. The hydrogen atom and all that sort

597
00:21:54,434 --> 00:21:55,095
of stuff.

598
00:21:55,875 --> 00:21:56,934
I mean, is

599
00:21:57,679 --> 00:21:58,339
is it

600
00:21:58,720 --> 00:22:01,039
is quantum information taught now? I mean, I

601
00:22:01,039 --> 00:22:03,539
know that I don't think you you teach,

602
00:22:03,919 --> 00:22:05,599
do you? Or maybe maybe you do teach.

603
00:22:05,599 --> 00:22:06,740
I I do. You do Waterloo.

604
00:22:07,119 --> 00:22:08,640
I actually, I teach in the the master's

605
00:22:08,640 --> 00:22:10,565
program that we have here at Perimeter. So

606
00:22:10,565 --> 00:22:12,845
we have the Psi one year master's program.

607
00:22:12,845 --> 00:22:14,845
Right. And do do you teach Yeah. I

608
00:22:14,845 --> 00:22:17,325
teach quantum information there, actually. Right. I see.

609
00:22:17,325 --> 00:22:19,265
Yeah. Okay. And is it,

610
00:22:20,924 --> 00:22:22,845
I mean, do or, you know, sort of

611
00:22:22,845 --> 00:22:25,890
early career well, master's students, so they do

612
00:22:25,890 --> 00:22:27,349
they find it really fascinating?

613
00:22:27,730 --> 00:22:29,650
I mean, more fascinating than this than the

614
00:22:29,650 --> 00:22:31,029
simple harmonic oscillator.

615
00:22:31,490 --> 00:22:33,910
Yeah. I mean, I think it's it's a

616
00:22:34,849 --> 00:22:37,190
it's a quick route to getting people excited

617
00:22:37,250 --> 00:22:37,664
about

618
00:22:38,225 --> 00:22:40,325
physics and about quantum mechanics. And,

619
00:22:41,345 --> 00:22:42,945
I definitely see a lot of excitement from

620
00:22:42,945 --> 00:22:44,705
my students and a lot of a lot

621
00:22:44,705 --> 00:22:47,345
of interest, like, from multiple different fields. You

622
00:22:47,345 --> 00:22:49,345
know? I don't know. They're interested in gravity.

623
00:22:49,345 --> 00:22:51,279
They're interested in condensed matter, but they wanna

624
00:22:51,279 --> 00:22:53,039
learn a little bit of quantum information as

625
00:22:53,039 --> 00:22:55,059
well. They've heard that it's that it's useful.

626
00:22:56,640 --> 00:22:57,839
Yeah. So you're starting to see a lot

627
00:22:57,839 --> 00:22:59,680
of that. And then there's kind of a

628
00:22:59,680 --> 00:23:01,359
whole other set of people that are interest

629
00:23:01,440 --> 00:23:04,079
interested in or excited about quantum information because

630
00:23:04,079 --> 00:23:06,714
of its applications. Right? Because they're excited about

631
00:23:06,714 --> 00:23:10,634
quantum computing or quantum communication or these sort

632
00:23:10,634 --> 00:23:12,954
of practical things that could happen down the

633
00:23:12,954 --> 00:23:13,454
road.

634
00:23:14,474 --> 00:23:16,714
Yeah. I mean, I I've I've I've just

635
00:23:16,714 --> 00:23:17,695
amazed that

636
00:23:18,240 --> 00:23:21,299
quantum well, I suppose quantum computation, technology,

637
00:23:22,079 --> 00:23:24,799
information, you know, the, it it seems like

638
00:23:24,799 --> 00:23:25,700
it's it's a

639
00:23:26,400 --> 00:23:27,839
I don't think it's wrong to call it

640
00:23:27,839 --> 00:23:30,079
a revolution really in in sort of our

641
00:23:30,079 --> 00:23:30,579
understanding

642
00:23:30,880 --> 00:23:33,414
of of the quantum world. It's, you know,

643
00:23:33,414 --> 00:23:34,855
I think it's a really good time to

644
00:23:34,855 --> 00:23:35,595
be a physicist.

645
00:23:36,535 --> 00:23:37,734
I I think so. I think it's a

646
00:23:37,734 --> 00:23:40,474
very exciting field right now. Well, that's great,

647
00:23:40,855 --> 00:23:42,615
Alex. Thanks so much for coming on the

648
00:23:42,615 --> 00:23:44,394
podcast, and hopefully we've encouraged

649
00:23:44,775 --> 00:23:48,000
some listeners to perhaps look into the intersection

650
00:23:48,000 --> 00:23:50,740
between quantum gravity and, quantum information.

651
00:23:51,359 --> 00:23:52,820
Great. Well, thanks for having me.

652
00:24:00,434 --> 00:24:03,234
That was Alex May in a conversation I

653
00:24:03,234 --> 00:24:07,014
recorded at the Perimeter Institute for Theoretical Physics.

654
00:24:07,554 --> 00:24:10,994
Thanks to Alex for a fascinating chat about

655
00:24:10,994 --> 00:24:12,054
all things quantum,

656
00:24:12,755 --> 00:24:14,774
and thanks to you for listening.

657
00:24:15,640 --> 00:24:18,359
We'll be back again next week. I'm Hamish

658
00:24:18,359 --> 00:24:18,859
Johnston,

659
00:24:19,160 --> 00:24:21,740
and our producer is Fred Isles.