The Quantum Internet is Drawing Near, But What Exactly Is It?

In February 2020, researchers from the U.S. Department of Energy's Argonne National Laboratory and the University of Chicago announced their success in achieving quantum entanglement—where two minuscule particles become linked, with their behaviors mirroring one another—across a 52-mile (83.7 kilometer) quantum-loop network in suburban Chicago.

If you're not a physicist versed in quantum mechanics—the study of matter and energy at the smallest scales, which behaves in ways that defy our everyday experiences—you might be wondering what all the excitement is about.

However, the researchers' accomplishment could mark a pivotal moment in the creation of a far more powerful version of the internet within the next few decades. Unlike the bits used by today's networks, which can only represent either 0 or 1, the future quantum internet will employ qubits of quantum information, capable of representing an infinite range of values. (A qubit is the basic unit of information for a quantum computer, similar to how a bit functions in traditional computers).

This would significantly expand the quantum internet's bandwidth, enabling the connection of extremely powerful quantum computers and other devices, while supporting massive applications that aren't feasible with our current internet infrastructure.

"A quantum internet will serve as the foundation of a quantum ecosystem, where computers, networks, and sensors interact in a fundamentally new way, with sensing, communication, and computing seamlessly working as a unified system," says David Awschalom in an email. He is a professor of spintronics and quantum information at the Pritzker School of Molecular Engineering at the University of Chicago, as well as a senior scientist at Argonne, and was the leader of the quantum-loop project.

Understanding the Quantum Internet

So why is this necessary, and what exactly does it do? First of all, the quantum internet isn't meant to replace the current internet, but rather to complement it or branch off from it. It would address some of the major challenges facing today's internet. For example, a quantum internet would provide significantly stronger defenses against hackers and cybercriminals. Currently, when Alice in New York sends a message to Bob in California over the internet, the message travels more or less directly from coast to coast. Along the way, the transmission signals degrade; repeaters read the signals, amplify them, and correct any errors. But this process opens the door for hackers to intercept and "break into" the communication.

Quantum messages, however, wouldn't face such issues. Quantum networks use photons—particles of light—to transmit messages that are immune to cyberattacks. Rather than relying on complex encryption, as Ray Newell, a researcher at Los Alamos National Laboratory explains, quantum physics' strange rules would secure communication. With quantum information, "you can't replicate it or split it, and even observing it alters its state." In fact, attempting to intercept a message destroys it, as Wired magazine points out. This makes encryption vastly more secure than anything available today.

"A simple way to grasp the idea of the quantum internet is by understanding quantum teleportation," says Sumeet Khatri, a researcher at Louisiana State University in Baton Rouge, via email. He and his team have published a paper exploring the potential of a space-based quantum internet, where satellites would continuously transmit entangled photons to Earth's surface, as discussed in this Technology Review article.

"Quantum teleportation isn't quite the same as what you'd see in science fiction films," Khatri clarifies. "In quantum teleportation, two individuals wishing to communicate share a pair of entangled quantum particles. Then, using a series of operations, the sender can transmit any quantum data to the receiver (although it can't occur faster than light, contrary to popular belief). This shared entanglement among pairs of individuals worldwide forms the essence of the quantum internet. The main research challenge is how to effectively distribute these entangled pairs globally."

Once large-scale implementation becomes feasible, the quantum internet would be so incredibly fast that remote clocks could be synchronized with a precision a thousand times greater than today's top atomic clocks, as detailed in Cosmos magazine. This would vastly improve GPS accuracy and enable mapping Earth's gravitational field in unprecedented detail, allowing scientists to detect gravitational wave ripples. It could also facilitate the teleportation of photons from distant visible-light telescopes, linking them into a massive virtual observatory.

"You could potentially observe planets orbiting other stars," says Nicholas Peters, leader of the Quantum Information Science Group at Oak Ridge National Laboratory.

It could also become possible for networks of ultra-powerful quantum computers around the world to collaborate and produce highly intricate simulations. This might allow scientists to gain deeper insights into the behavior of molecules and proteins, for instance, leading to the development and testing of new medications.

It may also assist physicists in solving some of the universe's long-standing mysteries. "We don't yet have a full understanding of how the universe operates," says Newell. "We grasp quantum mechanics fairly well, but the implications are still unclear. The picture becomes blurry where quantum mechanics intersects with our everyday experiences."

Challenges in Constructing the Quantum Internet

However, before any of this can come to fruition, researchers must determine how to construct a quantum internet. Given the strange nature of quantum mechanics, this will not be a simple task. "In the classical world, you can encode information, store it, and it won't degrade," Peters says. "In the quantum world, however, you encode information, and it begins to degrade almost immediately."

Another challenge is that the energy corresponding to quantum information is incredibly low, making it difficult to prevent interactions with the surrounding environment. As Newell points out, "In many instances, quantum systems only function at extremely low temperatures." Another approach is to work in a vacuum by removing all the air.

For a quantum internet to become a reality, Newell states, we'll need various pieces of hardware that haven't been developed yet. Therefore, it's difficult to predict exactly when the quantum internet will be operational, though one Chinese scientist has predicted it could be as early as 2030.