Emergent Topology Beyond the Particle Picture

<v Speaker 1>Welcome to the quart Side Quantum Physics Podcast, an exploration
<v Speaker 1>of the fundamental structure of reality, where quantum laws govern matter, energy,
<v Speaker 1>and information. Here, uncertainty is a feature, not a flaw,
<v Speaker 1>and understanding begins with the smallest scales.
<v Speaker 2>Welcome back. We are getting into something today that I
<v Speaker 2>genuinely think is going to change the way you look
<v Speaker 2>at the world. And I don't mean that in a
<v Speaker 2>spiritual journey kind of sense, though it does get pretty.
<v Speaker 3>Close, it gets weirdly close.
<v Speaker 2>Yeah, I mean it in the literal physical sense of
<v Speaker 2>looking at a table or a wall or your own
<v Speaker 2>hand and just questioning what is what is actually there?
<v Speaker 3>It's a fundamental shift. I mean usually when we talk
<v Speaker 3>about science news, it's a faster chip, or a better battery,
<v Speaker 3>or a new species of frog, a new species of
<v Speaker 3>frog exactly. We're adding to the library of things we know.
<v Speaker 3>But today we're talking about rewriting the I don't know
<v Speaker 3>the preface of.
<v Speaker 2>The book, the preface being what is stuff?
<v Speaker 3>Essentially, yes, at its very core.
<v Speaker 2>Because we're taught a very specific story when we're kids, right,
<v Speaker 2>I remember sitting in fifth grade science class and the
<v Speaker 2>teacher draws a circle on the chalkboard. Oh yeah. She
<v Speaker 2>puts a little dot in the middle of the nucleus
<v Speaker 2>and then draws these little orbits around it with other dots,
<v Speaker 2>the electrons, the bore model.
<v Speaker 3>It's iconic. It's on the side of every science museum.
<v Speaker 2>It is, and it's comforting, you know. It tells us
<v Speaker 2>that the universe is made of legos, right, tiny hard, distinct,
<v Speaker 2>little billiard balls that bounce around and stick together to
<v Speaker 2>make well, to make us.
<v Speaker 3>It's what we call the particle picture, and it has
<v Speaker 3>been the dominant way of thinking about reality for I mean,
<v Speaker 3>over one hundred years. It's practical, it's intuitive, and it
<v Speaker 3>works for almost everything we do in engineering. It works perfectly.
<v Speaker 2>But you are here today to tell me that a
<v Speaker 2>team of researchers in Vienna has basically taken a sledgehammer
<v Speaker 2>to that lego.
<v Speaker 3>Set h that is that's a pretty fair assessment. Yeah.
<v Speaker 3>We were looking at a paper that was just published
<v Speaker 3>in Nature Physics from t u ween that's the Vienny
<v Speaker 3>University of Technology, Okay, and they have discovered a state
<v Speaker 3>of matter that, according to that standard particle picture, should
<v Speaker 3>be well impossible. Impossible is a big word in physics.
<v Speaker 3>Impossible usually just means we haven't found the right math yet.
<v Speaker 3>But in this case, the contradiction is it's stark. They
<v Speaker 3>found a material that follows very strict geometric rules, what
<v Speaker 3>we call topology, but it does so without having any
<v Speaker 3>defined particles to actually follow those rules.
<v Speaker 2>Okay, hold on, that's the headline that melted my brain
<v Speaker 2>when I first read about this geometry without particles. Mm hm.
<v Speaker 2>It sounds like saying you have a traffic jam, but
<v Speaker 2>there are no cars, or a smile without the cat,
<v Speaker 2>the chessure cat. Yes, we are definitely going to get
<v Speaker 2>to that analogy because it's absolutely perfect. But before we
<v Speaker 2>go down that rabbit hole, let's set the stakes here.
<v Speaker 2>This isn't just about, you know, winning an argument in
<v Speaker 2>a faculty lounge. Why does this matter to the person
<v Speaker 2>listening right now?
<v Speaker 3>Because this discovery, I think is the key to the
<v Speaker 3>next generation of technology. We are hitting a wall with
<v Speaker 3>our current tech. You hear about Moore's law slowing down
<v Speaker 3>all the time, Our sensors are reaching their fundamental limits.
<v Speaker 3>This discovery, this breakdown of the particle picture, it opens
<v Speaker 3>a door to censors that are virtually immune to noise.
<v Speaker 3>It opens the path to quantum computers that don't crash
<v Speaker 3>when you look at them, funny which they had to do,
<v Speaker 3>which they do, and maybe most impressively, it shows us
<v Speaker 3>how we could steer electricity without using magnetic fields.
<v Speaker 2>Steering electricity without magnets. How is that? Even?
<v Speaker 3>It sounds like magic, but it's just advanced geometry.
<v Speaker 2>Okay, I'm hooked.
<v Speaker 3>Huh.
<v Speaker 2>I want to understand how the cars disappeared, but the
<v Speaker 2>traffic jam stayed. Let's unpack this. Let's do it so
<v Speaker 2>to really understand why this is such a shock, we
<v Speaker 2>have to understand what we thought was true. We need
<v Speaker 2>to talk about this part picture, or as you called it,
<v Speaker 2>the approximation.
<v Speaker 3>Right, the useful fiction. So let's take a simple copy
<v Speaker 3>wire the cord that's charging your laptop right now. When
<v Speaker 3>you think about electricity flowing through that wire, what do
<v Speaker 3>you visualize?
<v Speaker 2>I picture a tube a highway, and inside that tube
<v Speaker 2>there are millions of little glowing balls electrons just racing
<v Speaker 2>from the wall socket to my computer.
<v Speaker 3>Exactly. You picture them as distinct entities, little spheres. They
<v Speaker 3>have a position, it's here, they have velocity. It's moving
<v Speaker 3>that fast, right, And.
<v Speaker 2>If the wire gets hot, it's because those little balls
<v Speaker 2>are I don't know, crashing into things, greating friction.
<v Speaker 3>That is the Grood model from like nineteen hundred. It
<v Speaker 3>treats electrons like pinballs, and for i'd say ninety nine
<v Speaker 3>percent of electrical engineering, that model is fantastic work helps
<v Speaker 3>us design circuits, fuse boxes, toasters. But here is the
<v Speaker 3>secret that physicists don't really tell you until you're in
<v Speaker 3>grad school. It's not really true.
<v Speaker 2>I feel, but t trade My entire high school education
<v Speaker 2>is a lie.
<v Speaker 3>Don't be It's a very very useful fiction. In reality,
<v Speaker 3>Inside that wire you have billions of electrons interacting with
<v Speaker 3>billions of atomic nuclei, and they are all pushing and
<v Speaker 3>pulling on each other simultaneously. It's a it's a quantum mess.
<v Speaker 3>It's a soup.
<v Speaker 2>So how do we do any math if it's just
<v Speaker 2>a soup? Yeah, you can't calculate the trajectory of a soup.
<v Speaker 3>You can't. So we use a trick, a very very
<v Speaker 3>clever mathematical trick called quasi particles.
<v Speaker 2>Quasi particles, which implies fake particles.
<v Speaker 3>Almost particles, or as if particles. Think of it this way.
<v Speaker 3>Imagine you were at a really crowded concert. Okay, packed
<v Speaker 3>shoulder to shoulder. If you try to track one specific
<v Speaker 3>person moving from the back of the room to the stage,
<v Speaker 3>it's really hard. They are getting shoved, turned around, stuck impossibly.
<v Speaker 2>Yeah.
<v Speaker 3>But now imagine a small circle of empty space opens
<v Speaker 3>up in the crowd, a gap, and that gap moves
<v Speaker 3>towards the bar.
<v Speaker 2>Okay, I can track the gapees, I can see it
<v Speaker 2>moving exactly.
<v Speaker 3>But the gap isn't a person. It's the absence of people,
<v Speaker 3>but it moves like a person. It has a speed,
<v Speaker 3>it has a location. So in physics we treat that
<v Speaker 3>collective behavior, that gap, as if it were a particle.
<v Speaker 3>We give it a mass, we give it a charge,
<v Speaker 3>and we do the math on the gap, not on
<v Speaker 3>the whole crowd.
<v Speaker 2>That is genius. So we just we pretend the collective
<v Speaker 2>mess is actually just a bunch of simple, well behaved objects,
<v Speaker 2>and the math works out precisely.
<v Speaker 3>That is the entire foundation of modern solid state physics.
<v Speaker 3>We turn these incredibly complex interactions into simple quasi particles.
<v Speaker 3>And this has been the role. I mean, even the
<v Speaker 3>most advanced Nobel Prize winning theories of the last decade
<v Speaker 3>have relied on this fundamental assumption.
<v Speaker 2>It's the assumption that if you look closely.
<v Speaker 3>Enough, you can find a quasi particle to hang your
<v Speaker 3>hat on.
<v Speaker 2>So the idea is it might be complicated, but eventually,
<v Speaker 2>when you boil it down, it acts like a particle.
<v Speaker 3>Yes, that was the bedrock until now.
<v Speaker 2>Enter the disruptor. Hmmm, the Vienna team. They were looking
<v Speaker 2>at a specific material with a name that it sounds
<v Speaker 2>like a distinct lack of creativity. It does three four
<v Speaker 2>SN six.
<v Speaker 3>It's purely descriptive serium, ruthenium, and ten. It tells you
<v Speaker 3>the ingredients.
<v Speaker 2>I feel like they could have named it V and
<v Speaker 2>I or something cooler, but okay, or four SN six.
<v Speaker 2>What makes this alphabet soup so special?
<v Speaker 3>So it was called a heavy fermion system, which is
<v Speaker 3>just physicists speak for the electrons here interact really, really strongly.
<v Speaker 3>But the key isn't just the material itself, it's what
<v Speaker 3>they did to it. They cooled it down to temperatures
<v Speaker 3>that are just they're mind boggling.
<v Speaker 2>How cold are we talking?
<v Speaker 3>We are talking Millie Kilvin's a tiny tiny fraction of
<v Speaker 3>a degree above absolute zero.
<v Speaker 2>Okay, so that's colder than deep space, colder than the
<v Speaker 2>dark side of the.
<v Speaker 3>Moon, oh much much colder. And at these temperatures, this
<v Speaker 3>material enters a state called quantum criticality.
<v Speaker 2>That sounds like the alarm that goes off on a
<v Speaker 2>spaceship right before it explodes, warning quantum criticality reached.
<v Speaker 3>It's not quite that dramatic, but it's almost. It's more
<v Speaker 3>like a state of supreme indecision.
<v Speaker 2>Indecision. How can the material be indecisive?
<v Speaker 3>Okay, So imagine a coin spinning on a table. When
<v Speaker 3>it's spinning, is it heads or tails?
<v Speaker 2>It's neither, it's both at the same time, kind of right.
<v Speaker 3>Usually in nature, the coin eventually falls, water freezes into ice,
<v Speaker 3>steam condenses into water. A magnet aligns north or south.
<v Speaker 3>Nature likes to make a choice. We call that a
<v Speaker 3>phase transition.
<v Speaker 2>But in this material, it doesn't choose.
<v Speaker 3>In this quantum critical state, the material refuses to choose.
<v Speaker 3>It is poised on this razor's edge between two different
<v Speaker 3>possible states let's just say magnetic and non magnetic for simplicity,
<v Speaker 3>and it fluctuates wildly between them.
<v Speaker 2>So it's flickering.
<v Speaker 3>It's flickering exactly. Diana Kirschbaum, the lead author on the paper,
<v Speaker 3>She describes it as a state where the material cannot
<v Speaker 3>decide which one it wants to adopt. And because it's
<v Speaker 3>flickering so fast and so violently, the interactions between the electrons,
<v Speaker 3>they effectively become infinite definite interactions. That sounds bad, It's
<v Speaker 3>just it means there so strongly dominate everything. And when
<v Speaker 3>those interactions become that strong are trick the quasi particle,
<v Speaker 3>it breaks.
<v Speaker 2>The gap in the crowd disappears.
<v Speaker 3>The crowd becomes a mash pit, a liquid, a blur.
<v Speaker 3>You can no longer identify a distinct thing moving through
<v Speaker 3>the system. You can't say, here is a particle with
<v Speaker 3>mass X and velocity y. The mass becomes undefined, the
<v Speaker 3>velocity becomes undefined. The particle picture dissolves completely into a
<v Speaker 3>quantum soup.
<v Speaker 2>Okay, I'm with you. We have a soup. No billiard balls,
<v Speaker 2>no quasi particles, just raw, throbbing quantum chaos.
<v Speaker 3>And this is where the conflict arises, because logically, if
<v Speaker 3>you don't have.
<v Speaker 2>Particles, you can't have structure.
<v Speaker 3>You can have geometry.
<v Speaker 2>This brings us to the other big concept we need
<v Speaker 2>to tackle, topology.
<v Speaker 3>The twenty sixteen Nobel Prize a huge deal in physics.
<v Speaker 2>Right, this word gets thrown around a lot topological quantum matter.
<v Speaker 2>It sounds very, very fancy, but at its core it's
<v Speaker 2>about shapes.
<v Speaker 3>Right, It's about a very specific kind of shape analysis.
<v Speaker 3>Topology is often called rubber sheet geometry. In normal Euclidean geometry,
<v Speaker 3>a square is different from a circle because a square
<v Speaker 3>has corners and straight edges. Sure, in topology, we don't
<v Speaker 3>care about corners or straightness. We only care about one thing. Holes.
<v Speaker 2>This is where the donuts come in.
<v Speaker 3>It's always the donuts. So imagine you have a ball
<v Speaker 3>of plater. You can squash it, you can stretch it,
<v Speaker 3>you can twist it, you can flatten it into a pancake. Topologically,
<v Speaker 3>the ball and the pancake are exactly the same because.
<v Speaker 2>I didn't tear it or poke a new hole in it, exactly.
<v Speaker 3>But if I want to turn that ball into.
<v Speaker 2>A donut, you have to poke a hole through the middle.
<v Speaker 3>You have to perform a violent act. You have to
<v Speaker 3>tear the material. That tearing is a change in topology.
<v Speaker 3>So we classify objects by their number of holes. A
<v Speaker 3>ball has zero holes, a doughnut has one hole, a
<v Speaker 3>pretzel has three holes.
<v Speaker 2>What about a coffee mug. I've heard this one.
<v Speaker 3>A coffee mug has one hole, the one in the handle.
<v Speaker 3>So topologically a coffee mug is identical to a donut.
<v Speaker 3>You can imagine squishing the cup part of the mug
<v Speaker 3>into the ring of the handle without ever tearing it.
<v Speaker 2>Okay, I love that mental image. Okay, but electrons aren't donuts.
<v Speaker 2>They don't have handles. How does this apply to the
<v Speaker 2>quantum soup?
<v Speaker 3>It applies to the mathematics that describe the electrons, and
<v Speaker 3>we map out all their possible quantum states, their energy levels,
<v Speaker 3>their momentum, their spin. That map can have a shape,
<v Speaker 3>and sometimes that abstract mathematical map has a hole or
<v Speaker 3>a knot in it. A mathematical donut, mathematical donut exactly.
<v Speaker 3>And here's the crucial part. Just like a real donut
<v Speaker 3>keeps its hole, even if you dent it or take.
<v Speaker 2>A bite out of it, it's still the donut.
<v Speaker 3>It's still a donut. A topological material keeps its special
<v Speaker 3>electrical properties even if the wire is dirty or bent
<v Speaker 3>or has some impurities. It is incredibly robust.
<v Speaker 2>And this is why everyone is so excited about it.
<v Speaker 2>For technology, it's bulletproof physics.
<v Speaker 3>It is. But here's the catch. The entire definition of
<v Speaker 3>topological matter, the definition that won that Nobel prize, it
<v Speaker 3>relies on describing the shape of the particle.
<v Speaker 2>The shape of the dancers, not the dance.
<v Speaker 3>Yes, you analyze the wave function of the quasi particles
<v Speaker 3>to see if their mathematical space has a hole in it.
<v Speaker 2>Okay, so syllogism time. Let's see if I have this
<v Speaker 2>right premise, ie, you need particles to define topology. That
<v Speaker 2>was the assumption. Yere premi is two. This zero four
<v Speaker 2>EKA and six stuff in its quantum critical state has
<v Speaker 2>no particles.
<v Speaker 3>Correct, The picture dissolves conclusion.
<v Speaker 2>Therefore zero four s, A and six cannot have any
<v Speaker 2>topological properties.
<v Speaker 3>That was the prevailing wisdom. That was the logic. It's
<v Speaker 3>perfectly sound. If the particle picture breaks down, the topological
<v Speaker 3>classification should break down with it.
<v Speaker 2>And this wasn't just some abstract theoretical annoyance. This actually
<v Speaker 2>affected the scientists in the lab right. They hesitated it did.
<v Speaker 3>Science is done by humans, and humans have doubts and biases.
<v Speaker 3>There were some theoretical models, just math done on paper,
<v Speaker 3>hinting that maybe, just maybe this material could host topological states.
<v Speaker 3>But the experimental team at ten they were reluctant.
<v Speaker 2>Why why not just look?
<v Speaker 3>Because it felt like a complete wild goose chase. Professor
<v Speaker 3>Silka Bueler Passion, who led the team, she spoke about this,
<v Speaker 3>Why would you spend all this time and money and
<v Speaker 3>effort looking for a delicate ordered geometric structure and a
<v Speaker 3>material that is essentially a chaotic, fluctuating blur, like looking.
<v Speaker 2>For a perfect snowflake in a blender.
<v Speaker 3>That's a perfect analogy. It seemed contradictory, illogical, but they
<v Speaker 3>did it anyway. Curiosity prevailed. Diana Kirschbaum, the PhD student
<v Speaker 3>and first author on the paper, she pushed to investigate it.
<v Speaker 3>And it's just that beautiful spark of science. Right. The
<v Speaker 3>theory says X. My intuition says, why, let's just ask
<v Speaker 3>the universe what it actually thinks.
<v Speaker 2>So they fired up the world's coldest fridge. They cooled
<v Speaker 2>this stuff down to near absolute zero, and they went
<v Speaker 2>looking for the donut. How do you even look for
<v Speaker 2>a mathematical doughnut in a rock?
<v Speaker 3>You look for something called the Hall effect.
<v Speaker 2>Okay, we need to break this down. The Hall effect
<v Speaker 2>sounds familiar. Like from college.
<v Speaker 3>Physics as a classic. It was discovered way back in
<v Speaker 3>eighteen seventy nine. Here's the basic setup. You have a flat,
<v Speaker 3>thin strip of metal. You run a current through it,
<v Speaker 3>let's say from north to south.
<v Speaker 2>Okay, So electrons are flowing down the.
<v Speaker 3>Highway, cruising along. Now you bring a strong magnet close
<v Speaker 3>to the strip with its field pointing, say straight up.
<v Speaker 3>That magnetic field exerts a force, the Lorentz force that
<v Speaker 3>pushes the moving electrons sideways.
<v Speaker 2>Like a strong crosswind hitting the cars on the highway exactly.
<v Speaker 3>So the electrons instead of going straight, they start to
<v Speaker 3>curve and pile up on let's say the west side
<v Speaker 3>of the strip. That pile up of negative charge creates
<v Speaker 3>a voltage difference between the west side and the east side.
<v Speaker 3>We call that the Hall voltage.
<v Speaker 2>Okay, so the simple rule is no magnet equals no
<v Speaker 2>sideways voltage. You apply a magnet, you get a sideways voltage.
<v Speaker 3>Correct. That's the rule. But in topological materials there's a twist. Literally,
<v Speaker 3>if the mathematical structure of the material has that doughnut shape,
<v Speaker 3>that topological twist, it acts like an internal magnetic field.
<v Speaker 2>The material itself pushes the electrons to the side.
<v Speaker 3>The geometry of the quantum states pushes the electrons. This
<v Speaker 3>is called the anomalous Hall effect. You see the electrons
<v Speaker 3>swerving to the side without applying any external magnet at all.
<v Speaker 2>So it's like the banked turn on a racetrack. The
<v Speaker 2>cars turn not because the driver is steering, but because
<v Speaker 2>the road itself is curved.
<v Speaker 3>That is a perfect analogy. The very curvature of the
<v Speaker 3>quantum wave function acts precisely like a banked turn for electrons.
<v Speaker 2>So the team in Vienna hooks up their electrodes to
<v Speaker 2>this particleless soup, expecting to see what nothing.
<v Speaker 3>If the logic held that no particles means no topology,
<v Speaker 3>they should have seen absolutely zero anomalous Hall effect. The
<v Speaker 3>cars shouldn't swerve because well, there are no cars and
<v Speaker 3>there's no road.
<v Speaker 2>And what did they see.
<v Speaker 3>They saw a massive signal, a huge anomalous Hall effect.
<v Speaker 3>The electrons were swerving hard without a magnet, Without any
<v Speaker 3>external magnet, they found the signature of the doughnut.
<v Speaker 2>But but how you.
<v Speaker 3>Just told me. The particles dissolved, the cars aren't there.
<v Speaker 2>That's the breakthrough, that's the discovery. They found that the topology.
<v Speaker 2>The geometry was surviving the death of the particles, the smile.
<v Speaker 3>Of the chessure cat hanging in the air after the
<v Speaker 3>cat has faded.
<v Speaker 2>Away, precisely and it gets even weirder, even more profound.
<v Speaker 2>They mapped out when this effect happened, and they found
<v Speaker 2>that this swerving, this topological signal was at its strongest
<v Speaker 2>exactly when the quantum critical fluctuations were the most violent.
<v Speaker 3>Wait a second, so the chaos wasn't destroying the geometry.
<v Speaker 2>The chaos was creating the geometry.
<v Speaker 3>That is completely counterintuitor.
<v Speaker 2>It turns everything on its head. They did a control experiment.
<v Speaker 2>If they applied pressure or a strong magnetic field to
<v Speaker 2>force the material to choose a state, to stop fluctuating
<v Speaker 2>and become a normal, well behaved material, again the topological
<v Speaker 2>effect vanished.
<v Speaker 3>So if you fix the material's identity crisis, the magic
<v Speaker 3>goes away, exactly the doughnut shape. The topology only exists
<v Speaker 3>because of the quantum criticality. The intense collective interactions between
<v Speaker 3>the electrons that infinite mosh pit are what actually generate
<v Speaker 3>the topological state.
<v Speaker 2>So this is a fundamentally new thing. They had to
<v Speaker 2>coin a new term for it.
<v Speaker 3>They did. They're calling it an emergent topological semi metal emergent.
<v Speaker 2>Yeah, that's a heavy word in physics.
<v Speaker 3>It is It implies that the property arises from the
<v Speaker 3>collective behavior. It's not a property that's built into the
<v Speaker 3>individual pieces. It emerges from the complex way they dance together.
<v Speaker 2>It's like consciousness, right. You can't find consciousness in a
<v Speaker 2>single neuron. It's not a property of the neuron. Yeah,
<v Speaker 2>but you put billions of them together and let them interact,
<v Speaker 2>and suddenly you have a mind.
<v Speaker 3>That's a fantastic parallel. You can't find the topology in
<v Speaker 3>a single electron, but you put them in this critical,
<v Speaker 3>fluctuating state, and this robust topological order emerges from the chaos.
<v Speaker 2>They didn't just observe this, they explained it too. I read.
<v Speaker 2>They brought in some heavy theoretical backup.
<v Speaker 3>Yes, and from Rice University in Texas, led by professor
<v Speaker 3>Kimyosi and Lei Chen. They did the heavy lifting on
<v Speaker 3>the mathematical modeling. They built a new theoretical framework that
<v Speaker 3>combines quantum criticality, the fluctuations with the concepts of topology.
<v Speaker 2>They wrote the Peace Treaty between Chaos and order.
<v Speaker 3>In a way. Yes, and they proved mathematically that you
<v Speaker 3>don't need the particle for the geometry to exist. Professor
<v Speaker 3>Bueler Passion summed it up perfectly in their press release.
<v Speaker 3>She said, a particle picture is not required.
<v Speaker 2>That is such a dry scientific way to say something
<v Speaker 2>that basically breaks reality. A particle picture is not required.
<v Speaker 2>It's like saying, oh, by the way, gravity is optional
<v Speaker 2>on Tuesdays.
<v Speaker 3>It feels that big because it generalizes the entire concept
<v Speaker 3>of topology. It moves it from being a property of
<v Speaker 3>matter of particles to being a property of fields or
<v Speaker 3>interactions themselves. The geometry is more fundamental than the stuff.
<v Speaker 2>So we've established that the universe is fundamentally weirder than
<v Speaker 2>we thought. But let's bring this back to the why
<v Speaker 2>should I care? Factor? Because you mentioned earlier this is
<v Speaker 2>a blueprint for new technology.
<v Speaker 3>It is a huge one. Now that we know this
<v Speaker 3>state of matter exists, we can go out and hunt for.
<v Speaker 2>It, hunt for aware in other weird materials.
<v Speaker 3>In a whole class of materials we were previously ignoring.
<v Speaker 3>See before this, physicists who were looking for new topological materials,
<v Speaker 3>they generally avoided quantum critical systems. They thought, oh, that's
<v Speaker 3>too messy. The quasi particles aren't well defined, the math
<v Speaker 3>won't work there.
<v Speaker 2>They were looking for their keys under the street light
<v Speaker 2>because that's where the light was, not where they dropped
<v Speaker 2>them exactly.
<v Speaker 3>Now we know the keys are actually in the dark,
<v Speaker 3>messy alleyway, and we have a map to find them.
<v Speaker 3>This opens up a huge class of materials. We call
<v Speaker 3>them strongly correlated electron systems to be potential technological gold mines.
<v Speaker 2>Okay, so what are we building with this gold.
<v Speaker 3>Let's start with sensors. Remember the robustness, the undendable donut, right.
<v Speaker 3>Because the electrical signal in these materials is protected by
<v Speaker 3>g geometry, not by the purity of the material, it
<v Speaker 3>is incredibly resistant to noise, temperature fluctuations, small impurities in
<v Speaker 3>the crystal vibrations. They don't mess up the signal nearly
<v Speaker 3>as much.
<v Speaker 2>So if I'm building an ultrasensitive sensor for an MRI
<v Speaker 2>machine or a satellite telescope or a gravity wave detector, you.
<v Speaker 3>Get a signal that is fundamentally cleaner and more stable.
<v Speaker 3>You get a level of sensitivity that we currently can't
<v Speaker 3>achieve with conventional electronics.
<v Speaker 2>That's huge Okay, what about energy.
<v Speaker 3>That steering without magnets aspect the anomalous Hall effect right now,
<v Speaker 3>to manage power flows or steer currents and computer chips,
<v Speaker 3>we use a lot of components that rely on resistance,
<v Speaker 3>which creates waste heat.
<v Speaker 2>That's the heat that's killing my phone's battery life.
<v Speaker 3>It is. Now, imagine if the material steered the current
<v Speaker 3>for you simply because of its intrinsic geometric shape. It's
<v Speaker 3>a frictionless process. It's what we call dissipationless.
<v Speaker 2>Just flows like water down a perfectly shaped hill.
<v Speaker 3>Exactly. It could lead to a new generation of electronics
<v Speaker 3>that are drastically more energy efficient.
<v Speaker 2>And then there is the big one, the one everyone
<v Speaker 2>always talks about, quantum computing.
<v Speaker 3>Holy Grail.
<v Speaker 2>We've been hearing about quantum computers for twenty years. It's
<v Speaker 2>always they're coming next year. Why is it taking so long?
<v Speaker 3>The short answer is because quantum states are incredibly fragile.
<v Speaker 3>A quibit, a quantum bit is like a soap bubble.
<v Speaker 3>If a stray photon hits it, if it vibrates too much,
<v Speaker 3>if it gets just a little too warm, pop, the
<v Speaker 3>information is lost. This is a process called decoherence.
<v Speaker 2>So we spend all our energy and resources trying to
<v Speaker 2>build these elaborate refrigerators to keep the bubble from popping.
<v Speaker 3>Right, But there is a different approach, a theoretical one
<v Speaker 3>called topological quantum.
<v Speaker 2>Computing, using the donut.
<v Speaker 3>Using the donut. Instead of storing the information in the
<v Speaker 3>fragile state of a single particle, like the orientation of
<v Speaker 3>a soap bubble, you store it in the topology. You
<v Speaker 3>store it in the existence of the whole itself.
<v Speaker 2>You can't pop a hole.
<v Speaker 3>You can't pop a hole exactly. You can shake the material,
<v Speaker 3>you could heat it up a little, you can have
<v Speaker 3>a defect, but the whole remains. The information is topologically protected.
<v Speaker 2>So this discovery in Vienna, hmm, it's a huge step
<v Speaker 2>towards that.
<v Speaker 3>It proves that these robust topological states can exist even
<v Speaker 3>in messy, fluctuating, hot quantum environments. It suggests that this
<v Speaker 3>emergent topology might be the best place to look to
<v Speaker 3>build a stable quibot that doesn't need to be perfectly
<v Speaker 3>isolated from the world.
<v Speaker 2>It's like nature's own error correction is built right in.
<v Speaker 3>That is a great way to put it. It's error
<v Speaker 3>correction by geometry I want to take.
<v Speaker 2>A step back and just look at the philosophical side
<v Speaker 2>of this for a minute, because we started this whole
<v Speaker 2>conversation with the simple idea that stuff is made of particles,
<v Speaker 2>the lego blocks, the lego blocks, and we have ended
<v Speaker 2>up with stuff is made of geometry that emerges from chaos.
<v Speaker 2>That's a big leap.
<v Speaker 3>It's a transition from a material view of the universe
<v Speaker 3>to a structural or informational view.
<v Speaker 2>It really feels like we are peeling back a layer
<v Speaker 2>of the onion and finding out there is no onion
<v Speaker 2>at the center. There's just the shape of where the
<v Speaker 2>onion used to be.
<v Speaker 3>There is a theory in fundamental physics. It's speculative, but
<v Speaker 3>it's gaining traction that perhaps everything is geometry, that particles
<v Speaker 3>like electrons and quirks aren't really fundamental things at all,
<v Speaker 3>but are just persistent knots in the fabric of space
<v Speaker 3>time or twists in an underlying quantum field.
<v Speaker 2>So if you can somehow untie the knot, the electron
<v Speaker 2>would just vanish.
<v Speaker 3>It would vanish, leaving behind flat space time. And this discovery,
<v Speaker 3>the fact that you can have the topological property the
<v Speaker 3>geometry without the well defined particle is a strong piece
<v Speaker 3>of experimental evidence for that worldview. It suggests that the
<v Speaker 3>geometry is the more fundamental reality. The particle is just
<v Speaker 3>a temporary symptom of the geometry that is profound.
<v Speaker 2>It means that when I touch this table, I'm not
<v Speaker 2>actually touching matter. I'm touching a geometric rule says your
<v Speaker 2>hand cannot pass through this region of space.
<v Speaker 3>You are interacting with a topology that resists your hand. Ye.
<v Speaker 2>Yes, I'm going to be thinking about that for a week.
<v Speaker 3>That's Yeah, it's the kind of thought that keeps physicists
<v Speaker 3>up at night, But in a good way.
<v Speaker 2>It means there was still so much to discover. We
<v Speaker 2>really thought we had the rule book pretty.
<v Speaker 3>Much written, and nature just handed us a new appendix.
<v Speaker 2>Or maybe a whole new volume, probably a whole new volume.
<v Speaker 3>Yeah.
<v Speaker 2>Before we wrap up, I just want to give a
<v Speaker 2>shout out to the human element here again, because it
<v Speaker 2>would have been so easy for that team at t
<v Speaker 2>Uwaine to say the logic says, no, let's save the money,
<v Speaker 2>let's not run the experiment.
<v Speaker 3>It would have been the completely rational choice based on
<v Speaker 3>existing theory.
<v Speaker 2>Look, they didn't, Yeah, they chose curiosity over convention. They
<v Speaker 2>chose to look in the blender for the snowflake.
<v Speaker 3>And that is how all the best science happens. It
<v Speaker 3>happens when someone looks at a contradiction and says, that's funny,
<v Speaker 3>instead of that's impossible.
<v Speaker 2>That's funny. Isaac Asimov said that was the most important
<v Speaker 2>phrase in science.
<v Speaker 3>It was absolutely right.
<v Speaker 2>So for the listener who is currently feeling like their
<v Speaker 2>physical reality has been slightly dissolved around them, what is
<v Speaker 2>the one big thing they should take away from all this?
<v Speaker 3>I would say this, don't get too attached to your models.
<v Speaker 3>The particle picture is a model. It's a tool. It's
<v Speaker 3>a great tool for fixing a toaster or building a bridge,
<v Speaker 3>but it's not the ultimate truth. The universe is more fluid,
<v Speaker 3>it's more emergent, and it's surprisingly more geometric than our
<v Speaker 3>simple pictures allow.
<v Speaker 2>And sometimes you have to lose the cat to really
<v Speaker 2>find the smile.
<v Speaker 3>I couldn't have set it better myself.
<v Speaker 2>Thank you so much for guiding us through the quantum soup.
<v Speaker 2>My brain hurts, but in the best possible way.
<v Speaker 3>It was a pleasure, always fun to question reality.
<v Speaker 2>And to everyone listening, keep asking the simple questions. Ask
<v Speaker 2>what stuff is made of, Ask why the light comes on,
<v Speaker 2>And when the answer doesn't quite make sense, dig deeper.
<v Speaker 2>We'll see you next time.