The quantum internet is coming.
China, leaps and bounds ahead of the United States and the rest of the world, has vastly expanded the scope of quantum signaling. As recently as 2014, laboratory quantum effects maxed out at distances of just meters or — at most — a kilometer. Now, thanks to China’s advanced Micius satellite, researchers are achieving quantum entanglement and teleportation across hundreds of miles of distance.
That’s a big deal. Two entangled particles, no matter how far they’re separated in space, function as the same particle. Whatever properties one has, the other will as well. Quantum teleportation doesn’t actually send a whole particle through the ether into another point in space, but it does send information between two entangled particles. Pull that off at a global scale, and you’re well on your way to a true quantum internet.
So at the pace things are moving, there’s a very real chance you’ll see the rise of the quantum internet in your lifetime. What will that mean?
The most immediate benefit of the quantum internet is security. A set of entangled particles can operate like a kind of uncrackable passcode. Each particle in your theoretical quantum-internet computer contains a qubit — the smallest chunk of quantum computing information — shared undetectably with its entangled twin in the computer you’re sending a message to.
Encode your message with that string of qubits, and only the computer at the other end will be able to decode it. If, somehow, someone snuck in and read the qubits on one of you’re computers, you’d know — the act of observing a particle changes its quantum state in ways you can detect.
A heck of a lot more infrastructure
Huge obstacles remain between our present and our quantum-connected future. The biggest: Not only are quantum computers really hard to design and build, quantum relays have a whole host of difficulties not present in the regular internet.
If you’re reading this, you’re probably connected to the internet right now. But that doesn’t actually tell us much about how you’re connected. Because the kinds of information that make up this text, the images around it, and the website Inverse don’t depend on any particular kind of signal. We can send them over wires, through an ethernet cable to your computer. We can send them through the air to your phone or laptop using radio waves. We can send them using light through a fiber optic cable. Heck, if we were adventurous enough we could build a fire and send the data bit-by-bit through smoke signals — cover the smoke for a moment to represent a zero, release it to represent a one, and spell out the entire binary code.
Not so with quantum uplinks and downlinks. Each quantum signal depends on separating two entangled particles, probably photons, across the vast distances between computers. That’s really hard. Fiber optic cables start to destroy the photons over long enough distances. They won’t travel through electrical wires. You can’t just put them in a jar and ship ‘em. And each pair of entangled protons are single-use. Read them once, and they can’t give you any new passcodes. Bummer.
Right now, China’s solved the problem on a very small scale by beaming entangled photons up and down through hyper-advanced relay stations on Earth and aboard Micius up in space. But that’s not very scalable. Reduce the precision of the transmitters and receivers, and the photons are going to get lost.
No one has yet come up with a good method for doing this kind of task cheaply and reliably. It’s probably going to involve a whole bunch of satellites though.
Some folks, like the quantum physicist Ronald Hanson, imagine a world where most people use fully conventional computers. But, he explained in an interview with Phys.org if they need to send a quantum-secure message, they’ll head over to the local quantum relay to put it through. And if they just need to access a quantum computer to do some work, they’ll connect to it over the conventional internet.
New problem-solving tools
Scott Aaronson, a leading theoretical quantum computer scientist at MIT and author of the blog Shtetl Optimized, is less interested in the infrastructure challenges of the quantum internet than its computing possibilities. In an essay for Big Questions Online he imagines the quantum computing future and warns that average users might be disappointed:
“We were promised the dawn of a new era!” they cry. “We were promised that quantum computers, once they finally arrived, would transform the lives of ordinary people just as the transistor, telephone, and internal combustion engine did for earlier generations. I mean, look at the popular magazine articles from a few decades ago. They said that quantum computers would harness the mind-boggling power of multiple universes, by trying every possible solution in parallel. They said the practical applications were limitless… now you tell us that these gizmos are mostly good for ‘quantum simulation,’ and a few other specialized tasks that excite you nerds, and might someday lead to important discoveries, but have little immediate bearing on the average person’s life? And some of you even knew this all along? Phooey! You quantum computing people should be hauled into court, for perpetrating a fraud on the public!”
In response, the quantum computing researchers protest that, from the very beginning, they’d tried to explain the real scope and limits of quantum information technologies to anyone who would listen, but their voices were drowned out by a drumbeat of hype. As the quantum computing researchers see it, they were maltreated twice: first when many journalists, investors, and funding agencies ignored their sober scientific assessments in favor of snake-oil promises; then a second time when, in a cruel (if predictable) twist, they were the ones who got blamed when the sober assessments turned out to be correct.
The big differences between the quantum-connected internet and our current, drab, conventional one, he writes, are narrow.
People will send messages back and forth with a level of security far more advanced than any available today, but won’t think too much about it. They’ll likely have access to computers that can do certain kinds of difficult tasks — break all the encryption on an old, conventional computer, find all the prime factors of 56,892, design a better solar cell, or model a complicated biomolecule — at rates impossible today.
Certain kinds of puzzle-solving and pattern-matching might get easier too, he writes, like having your computer optimize factory production schedules or seeking patterns in stock data. (All of this, he adds, is a big “maybe.” No one yet knows for sure how fast a full-scale quantum computer can pull off these kinds of tasks.)
The biggest difference might not be the quantum computers themselves, but the secondary advantages that quantum computing research offers other fields: better medicines, better solar panels, faster conventional computers, and more efficient societies. But really, we just don’t know yet in any granular way what that will look like to an average person.
Hanson, in his interview, compared the present moment to the very earliest days of research into computer networks in the 1970s and ‘80s.
Now [compared to then] we are using the internet in a totally different way. We are all part of this huge global information highway. And I think some of the same things could happen with the quantum internet. It’s very hard right now to imagine what we could do (with it), and I think it is even harder than with the classical internet, because this concept of quantum entanglement is so counterintuitive that it is not easy to use your intuition to find applications for it.
The future, as ever, is very hard to predict.
“The world of 2040 has one important additional application of quantum computers: one so astonishing that, back in 2014, no one could possibly have imagined it,” Aaronson wrote. “Alas, because of that very fact, I can’t tell you what it is.”