How Light Could Help Build a Unified Quantum Internet

0:00Save with digital deals at Vons and Albertsons. This week at Vons and Albertsons, Ginny O, 93% lean ground turkey is 399 per pound, sold in a 3 pound tray with digital coupon limit two packages. And a 1 pound package of strawberries is 199 with digital coupon. Plus Kellogg's giant size cereal, 22.6 to 29.5 ounces, selected varieties are 299 each, with digital coupon limit three. Hurry in! Visit Vons or Albertsons.com for more deals and ways to save. Welcome to the Corkside Quantum Physics Podcast, an exploration of the fundamental structure of reality, where quantum laws govern matter, energy, and information. Here, uncertainty is a feature, not a flaw, and understanding begins at the smallest scales. If you wanted to connect the two most advanced quantum computers on Earth right now,

1:03you actually couldn't, like, they're entirely deaf to 100. Completely deaf, yeah. Which is wild, right? Because we hear all this hype about the promised future of quantum technology. You know, unhackable global communication networks, computing power that makes our current super computers look like, I don't know, abacuses. Right, yeah. And revolutionary sensors that could change medicine forever. Exactly. But there is this massive, completely hidden roadblock, preventing this future. And it's that the reason you don't have a global quantum internet today, is simply because our state of the art machines physically cannot talk to each other. They exist in, like, absolute isolation. Yeah, they really do. So today, we're exploring this brilliant, honestly, elegant solution to this exact bottleneck. It's a tiny gas-filled hollow tube that basically acts as a universal translator for light. It really is one of the most stubborn bottlenecks in modern physics. I mean, when you think about computers failing to communicate, your mind probably goes right to software, right? Oh, for sure. Like mismatched operating systems or a firewall issue.

2:06Exactly. Bad code, network errors. But in the quantum realm, the barrier isn't software at all. It is literally the physical wavelengths of light. Different quantum systems strictly demand completely different colors of light just to function. Right. And bridging that physical gap, getting those different colors of light to actually interact without completely destroying the incredibly delicate data they carry, is genuinely one of the hardest engineering challenges we face right now. I really want to unpack why this communication breakdown exists in the first place. Because, I mean, to anyone used to normal computers, it just sounds absurd. My laptop can send an email to a server halfway across the world. And it doesn't care what color the fiber optic light is. So why is the actual physical color of light such a monumental deal for a quantum machine? Well, to understand that, you have to look at the different physical components that will actually make up a future quantum internet. On the local level, you have your processors and the storage. These are systems like trapDiand devices or a rideberg atom platforms.

3:11Okay, let's pause right there because those are some heavy physics terms. What exactly are trapped ions and rideberg atoms doing? Basically, they are atoms suspended in a vacuum using electromagnetic fields. And we use lasers to manipulate their individual electrons. Okay. We use these exact atoms to store and process the quantum information. But to manipulate an atom, you have to hit it with a photon, a particle of light, that has the precise right amount of energy to interact with that specific atoms electron and show. Exactly right amount of energy. Exactly. And because of the laws of physics, the energy required for these atomic transitions almost always corresponds to light in the ultraviolet or visible ranges. That is their native environment. They operate entirely in these like high energy, very short wavelength colors. Okay, got it. So the quantum hard drives and the processors basically run on ultraviolet or visible light. Yeah, exactly. But if you want to take the information out of that processor in New York, say, and send it over a long distance to a processor in London, you can't use ultraviolet light.

4:12Why not? Because high energy lights scatters and degrades incredibly quickly over distance. It just won't make it. Instead, you have to use our existing global optical fiber networks. Which are already everywhere. Right, they're already laid under our oceans across continents. But they are physically optimized for telecommunications wavelengths, which sit firmly in the infrared range. Okay. Infrared light has a much longer wavelength and lower energy. So that allows it to travel for hundreds of miles through glass fibers with very minimal loss. Right. So, okay. So the local workers, the quantum processors, only operate in the equivalent of high-pitched dog whistles. That's the ultraviolet light. Yeah, that's a good way to put it. But the long distance phone lines, the fiber optics, they can only transmit low frequency hums. The infrared light. So if you can't perfectly translate the pitch from the dog whistle down to the low hum, the communication is just zero. That's the exact divide. The quantum nodes are physically deaf to the telecom fibers.

5:15And the telecom fibers simply cannot carry the ultraviolet signals. But wait, I have to push back here a little bit. We bounce light through fiber optic cables all the time. Transatlantic cables, they shift, they translate, and they amplify light continuously, right? And my data doesn't get corrupted. Sure, absolutely. We use prisms, we use filters, we shift wavelengths in classical physics every single day. Why can't we just run this quantum light through, like a standard optical translator, shift the wavelength from ultraviolet to infrared and just call it a day? Because classical communication and quantum communication encode data in completely different ways, like fundamentally different. How so? Well, when you send a regular email, the fiber optic cable is essentially just flashing light on and off. It's binary. Bright light is a one, no light is a zero. As long as the detector on the other end can tell the difference between loud and quiet, the message gets through fine. Right, the actual quality of the light doesn't matter much. Exactly. But in quantum mechanics, the information isn't just carried by the brightness of the light. It's encoded in a delicate property called the phase.

6:17Okay, um, define phase for us in this specific context. Phase basically describes the actual physical architecture of the light wave as it evolves through time and space. So imagine a wave moving across a pond. The phase is the precise timing and positioning of every single peak and trough of that wave. Okay, I can picture that. In quantum communication, the delicate state of entanglement, the actual connection that makes quantum computing powerful relies entirely on that exact physical wave structure remaining absolutely undisturbed. Wow. Okay, so translating these wavelengths in quantum mechanics isn't just like, um, like pouring water from a wide jug into a narrow glass. In the classical scenario, the water is the binary data. And as long as the water gets into the new container, it's fine. It's still water. Exactly. But this, this is more like trying to move a perfectly constructed 50 story house of cards from the back of a moving truck onto a stationary dining room table. That is a perfect analogy. And if you shift the wavelength using a standard classical translator,

7:21it's basically like hitting a pothole during that move. The whole structure collapses. Oh, man. Yeah. If the timing of those microscopic peaks and troughs shifts even slightly unpredictably during the color change, you lose what we call coherence. Coherence, meaning the phase staying in step. Yes. Coherence is simply the phase staying perfectly in step. If coherence drops, the entanglement is broken and your quantum data is permanently erased. You don't have a quantum network anymore. You just have a really, really expensive random number generator. That raises the stakes so much. We have to completely change the physical color of the light, change its energy, its frequency, without moving a single card in that fragile phase structure. It's incredibly difficult. How do you even begin to design a physical mechanism that does that? Well, it requires a highly specialized approach. And a massive breakthrough was actually recently modeled by a joint research team from UCLA, the SLAC and National Accelerator Laboratory,

8:21the University of Rochester and the University of Ottawa. Okay. They realized you couldn't use solid crystals or standard wires to do this translation, because solids tend to absorb or distort these specific wavelengths way too much. So what did they use? Instead, they modeled a setup using a holocore capillary fiber filled with xenon gas. A tiny hollow tube filled with gas. I mean, that sounds more like the inside of neon sign than the backbone of a next generation quantum internet. Why xenon? What makes that specific gas so special? Xenon is a heavy noble gas, which is the really crucial detail here. It has a very large dense electron clouds surrounding its nucleus. Okay. And because it's a noble gas, it doesn't want to chemically react with anything. It's highly transparent, meaning it won't just absorb the light and turn it into heat. Right. It just lets the light pass through. Mostly, yes. But because its electron cloud is so large, it's actually slightly, well, the best word is squishy. It's squishy when exposed to really intense electromagnetic fields,

9:22like the fields created by laser light. Squishy electron clouds. Yeah. And this allows for a very specific phenomenon called four-wave mixing. Four-wave mixing. Okay. Walk us through the actual mechanics of that. Like, what is physically happening inside that xenon filled tube when the light enters? Think of it as a meticulously choreographed collision of photons. You take your input light signal, the fragile quantum data coming from your ultraviolet processor, and you fire it into the xenon gas. Okay. The house of cards goes into the tube. Right. But to get the gas to act as a translator, you also fire a very strong, heavily calibrated intermediary laser pulse right alongside it. So you have the delicate quantum light and this powerful laser traveling through the gas at the exact same time? Yes. And as they travel, their electric fields interact with those squishy electron clouds of the xenon atoms. They temporarily distort the shape of the electron clouds. But the laws of physics dictate that energy and momentum must be perfectly conserved. So as the xenon atoms snap back to their normal state, they force the photons from the quantum signal

10:24and the powerful laser to combine, redistribute their energy and emit a completely new fourth wave. And this fourth wave is the translated light. Exactly. The energy has been mathematically redistributed so that this new photon comes out at the exact new wavelength you need, say, infrared. Okay. But what about the phase, the house of cards? That's the magic. Because the energy and momentum were strictly conserved during that interaction with the xenon atom, the original phase geometry that delicate house of cards is perfectly stamped onto the new infrared photon. That is incredible. The gas just acts as like a temporary mixing bowl where the energy is swapped, but the architectural blueprint of the wave is totally preserved. Exactly. And the range of translations they managed to model with the xenon tube is what really caught my eye. They successfully modeled taking infrared light at 1,030 nanometers and shifting it all the way to ultraviolet light at 343 nanometers. Which is a huge jump. Massive jump. And then they modeled taking the standard telecom band, which is 1,550 nanometers,

11:27the exact wavelength running through the fiber optic cables under our streets right now and converting it up to ultraviolet light at 308 nanometers and also visible light at 516 nanometers. Yeah. And those numbers are highly, highly intentional. The 550 nanometer band is the absolute standard for global telecommunications. If you want distance, you use 1,550. Right. On the other end, 308 nanometers and 516 nanometers are the precise wavelengths required to talk to specific atomic structures. For example, some rare earth quantum memories, which are solid state crystals used to store quantum states, they operate perfectly in that visible spectrum. Okay. And the trapped ions. Trapped ions often require specific ultraviolet wavelengths. So this single scene on to basically acts as universal adapter, capable of bridging the standard global telecom grid to almost any specialized quantum hardware currently in development. I mean, the theory is beautiful. The mechanism makes complete physical sense. But we have to look at the actual data. Like, did it actually preserve the phase? Did the house of cards survive?

12:28This highly energetic gas collision in the model? It did. The phase preservation was exceptionally strong. In their simulations, they didn't just test simple waves either. They threw highly complex phase structures at the gas things, like quadratic phase modulation, just to see if the process would smear the signal over time. To really stress test it. Exactly. And when they compared the phase of the original input signal to the new output signal, they found correlation values that consistently exceeded 0.95. Wow. And just for context, a 1.0 would be a mathematically perfect identical twin. Yes. And under their optimized conditions, the correlation actually rose above 0.99. That's insane. It really is. The transition from 1,515-anometer telepom light to 516-manometer visible light proved especially robust. It maintained that near-perfect 0.99 phase correlation across a very wide range of operational parameters. The blueprint of the wave survived the wavelength shift almost flawlessly. A 0.99 correlation is just stunning.

13:29But I mean, this is physics, which means you never get something for nothing, right? Oh, never. There's always a toll to pay. So what is the catch here? The catch is the eternal battle between fidelity and efficiency. To get those near-perfect 0.99 correlation scores, the intermediary laser pulse they fired into the gas had to have relatively low energy and a very narrow bandwidth. It had to be a gentle interaction. Very gentle. And under those gentle conditions, the phase transferred with almost zero distortion. But because the laser energy was low, only a small fraction of the light actually underwent the four-wave mixing process. So you get perfect translation, but the volume is incredibly low. Most of the light just doesn't convert, so the signal coming out the other end is quite faint. Exactly. Let's look at their actual efficiency numbers. For the infrared to ultraviolet conversion, they peaked at about 28% efficiency. The highly robust telecom divisible conversion hovered around 10.8%, and the telecom to ultraviolet only hit about 8.4%. Right. Now, intuitively, if you are an engineer looking at an 8% efficiency rate,

14:33your immediate thought is going to be, OK, just use a bigger laser. Right. Just blast it. Yeah. If you crank up the intensity of that intermediary pump laser, you force more photons to interact with the xenon gas, and your conversion efficiency will naturally skyrocket. But if you do that, I'm guessing you completely ruin the phase. You do. Why, though? What does a stronger laser actually do to the gas that ruins the translation? It triggers something called a nonlinear effect, specifically self-phase modulation. Normally, light passes through a medium-like gas or glass, and the medium pretty much stays the same. Right. But when you pump incredibly intense laser light into xenon gas, the electric field of the light is so strong that it actually alters the refractive index of the gas dynamically in real time. Wait, meaning the gas itself starts acting differently while the light is still moving through it? Precisely. As the refractive index fluctuates under the sheer power of that laser, it causes the light pulse to speed up and slow down at different points along its own wave.

15:35Oh, no. Yeah. The peaks of the wave might move slightly faster than the troughs. This instantly broadens the spectrum of the light, and it severely distorts the phase. You might get a 60% conversion efficiency, meaning plenty of light comes out the other end, but the timing of the wave is entirely smeared. So the house of cards is just blown over by the sheer force of the laser? Exactly. It just scatters. So it's this brutal seesaw. If you want maximum efficiency, a bright, powerful signal, the dynamic changes in the gas destroy your coherence, and you lose the quantum entanglement completely. Yep. But if you want perfect quantum coherence, you have to keep the laser gentle, which caps your efficiency at like 8% or 10%. This is literally the defining hurdle for the next generation of engineers building the quantum internet. Classical networking was mostly about just maximizing power and bandwidth, but quantum networking is going to require a wildly delicate balancing act. It sounds so tedious. It is. For every single node in the network,

16:35engineers will have to find the exact sweet spot between conversion efficiency and phase coherence. They have to tune the laser to be just strong enough to get a readable signal out the other end, but gentle enough to keep the refractive index of the xenon gas perfectly, perfectly stable. So knowing all of this, what does this actually mean for you listening to this? As we head toward this massive technological shift, I think it means that we are graduating from the era of pure theory and isolated lab experiments. We aren't just trying to build a solitary quantum computer in a basement anymore. No, the focus is definitely shifting to the physical plumbing. Yes, the plumbing. We are literally drafting the blueprints for the xenon-filled hollow fibers that will wire these isolated machines together into essentially a functional global brain. It's a profound shift in focus, though it is critical to note a reality check from the researchers themselves, particularly how Zen, the corresponding author of the study, everything we've discussed today, the .99 correlation, the specific manometer translations,

17:36the four-wave mixing dynamics, all of that was a rigorously modeled computational simulation. Right, so it proved that the math and the physical theories work flawlessly on paper. Yes, but as we know, the ultimate test in physics is always physical reality. The immediate next step for the scientific community is to physically manufacture these xenon hollow core fibers, stabilize them in an actual lab, and fire real, physically entangled photons through them. To see if it actually holds up. Exactly. They have to prove that this near-perfect phase preservation definitively holds up against the messy, totally unpredictable noise of a real-world physical environment. Because the leap from a clean computer model to a messy physical lab is where the real fight always happens. But I want to leave you with a final thought to kind of mull over today. We've spent this time dissecting the microscopic mechanics, right? Electron clouds, refractive indices, and phase preservation. But if you zoom out for a second and look at the macro implication of this. It's huge! It is.

18:37If a tiny hollow tube of xenon gas can truly master this physical translation, if it allows a quantum computer in Tokyo to instantly and perfectly entangle its data with the Trapped-Ion memory drive in New York, without losing a single fraction of its phase structure, what actually happens to our traditional concepts of geography and distance? Right, because entanglement doesn't care about distance. Exactly. In a classical internet, data still has to travel. It takes time, even if it's just milliseconds. But if two machines across the planet can be perfectly entangled, acting as a single quantum system across thousands of miles, distance practically ceases to exist. Yeah. We are literally laying the groundwork for a future where the entire world can instantly share a single, unbroken quantum thought. Save with digital deals at Vons and Albertsons! This week at Vons and Albertsons, Ginny-O, 93% lean ground turkey is 399 per pound. Sold in a three-pound tray with digital coupon limit two packages. And a one-pound package of strawberries is 199 with digital coupon.

19:38Plus Kellogg's giant size serial, 22.6 to 29.5 ounces, selected varieties are 299 each, with digital coupon limit three. Hurry in! Visit Vons or Albertsons.com for more deals and ways to save.