Scientists think it will be particularly useful for problems that involve many variables, such as analyzing financial risk, encrypting data, and studying the properties of materials.
Researchers doubt that individuals will own personal quantum computers in near future. Instead, they’ll be housed at academic institutions and private companies where they can be accessed through a cloud service.
How does the quantum internet work?
Quantum computers use fundamental units of information similar to the bits used in classical computing. These are called “qubits.”
However, unlike conventional computer bits—which convey information as a 0 or 1—qubits convey information through a combination of quantum states, which are unique conditions found only on the subatomic scale.
For example, one quantum state that could be used to encode information is a property called “spin,” which is the intrinsic angular momentum of an electron. Spin can be thought of like a tiny compass needle that points either up or down. Researchers can manipulate that needle to encode information into the electrons themselves, much like they would with conventional bits—but in this case, the information is encoded in a combination of possible states. Qubits are not either 0 or 1, but rather both and neither, in a quantum phenomenon called superposition.
This allows quantum computers to process information in a wholly different way than their conventional counterparts, and therefore they can solve certain types of problems that would take even the largest supercomputers decades to complete. These are problems like factoring large numbers or solving complex logistics calculations (see the traveling salesman problem). Quantum computers would be especially useful for cryptography as well as discovering new types of pharmaceutical drugs or new materials for solar cells, batteries, or other technologies.
But to unlock that potential, a quantum computer must be able to process a large number of qubits—more than any single machine can manage at the moment. That is, unless several quantum computers could be joined through the quantum internet and their computational power pooled, creating a far more capable system.
There are several different types of qubits in development, and each comes with distinct advantages and disadvantages. The most common qubits being studied today are quantum dots, ion traps, superconducting circuits, and defect spin qubits.
What can the quantum internet do?
Like many scientific advances, we won’t understand everything the quantum internet can do until it’s been fully developed.
Few could imagine 60 years ago that a handful of interconnected computers would one day spawn the sprawling digital landscape we know today. The quantum internet presents a similar unknown, but a number of applications have been theorized and some have already been demonstrated.
Thanks to qubits’ unique quantum properties, scientists think the quantum internet will greatly improve information security, making it nearly impossible for quantum encrypted messages to be intercepted and deciphered. Quantum key distribution, or QKD, is a process by which two parties share a cryptographic key over a quantum network that cannot be intercepted. Several private companies already offer the process, and it has even been used to secure national elections.
At the same time, quantum computers pose a threat to traditional encrypted communication. RSA, the current standard for protecting sensitive digital information, is nearly impossible for modern computers to break; however, quantum computers with enough processing power could get past RSA encryption in a matter of minutes or seconds.
A fully-realized quantum network could significantly improve the precision of scientific instruments used to study certain phenomena. The impact of such a network would be wide-ranging, but early interest has centered on gravitational waves from black holes, microscopy, and electromagnetic imaging.
Creating a purely quantum internet would also relieve the need for quantum information to transition between classical and quantum systems, which is a considerable hurdle in current systems. Instead, it would allow a set of individual quantum computers to process information as one conglomerate machine, giving them far greater computational power than any single system could command on its own.
“The quantum internet represents a paradigm shift in how we think about secure global communication,” said David Awschalom, the Liew Family Professor in Molecular Engineering and Physics at the University of Chicago, director of the Chicago Quantum Exchange, and director of Q-NEXT, a Department of Energy Quantum Information Science Center at Argonne. “Being able to create an entangled network of quantum computers would allow us to send unhackable encrypted messages, keep technology in perfect sync across long distances using quantum clocks, and solve complex problems that one quantum computer might struggle with alone–and those are just some of the applications we know about right now. The future is likely to hold surprising and impactful discoveries using quantum networks.”
How far off is the quantum internet?
To date, no one has been able to successfully create a sustained quantum network on a large scale, but there have been major advances.
In 2017 researchers at the University of Science and Technology of China used lasers to successfully transmit entangled photons between a satellite in orbit and ground stations more than 700 miles below. The experiment showed the possibility of using satellites to form part of a quantum network, but the system was only able to recover one photon out of every 6 million—too few to be used for reliable communication.