BURSTThe quantum Internet can be a mind-bending, sci-fi sounding concept, but it’s also one that is getting closer, albeit slowly, to becoming a reality.
“Quantum Internet” is the term given to a global network that connects devices like quantum computers and sensors, which operate on the principles of quantum mechanics, not traditional computing.
The quantum Internet network transmits information encoded in qubits, rather than the bits used by traditional computers hooked up to the traditional Internet. Because the quantum Internet relies on principles of quantum mechanics, it results in some very weird, very powerful capabilities.
The quantum Internet is made up of quantum computers networked together. Those quantum computers follow principles of quantum mechanics like superposition, which allows qubits to represent a zero and a one simultaneously. They also rely on quantum entanglement, which links qubits regardless of the distance of their physical separation.
When connected, the quantum Internet of linked quantum computers can do things our current Internet cannot. That includes enabling inherently secure communications because, thanks to quantum mechanics, simply intercepting communications disturbs the state of the communications themselves. (In quantum mechanics, trying to intercept or eavesdrop on a message actually changes the composition of the qubits used to compose the message, which makes unauthorized access of the message detectable.)
In the last couple of years, the quantum Internet has made some big strides towards becoming a real technology deployed for real use cases in the real world. While it’s still early, experts see a bright future ahead for it, even if it might take a while.
The First Demonstration of Quantum Internet
Quantum Internet made significant progress this year. In April, it was reported that a team of researchers at Northwestern University succeeded in teleporting the quantum state of a photon across 18 miles of fiber optic cable used to carry Internet traffic. It was the first time researchers were able to actually transport quantum Internet traffic over infrastructure designed for traditional Internet traffic.
That provided a taste of what could happen if the quantum Internet was deployed at scale using the infrastructure behind today’s classical Internet, due to a few recent innovations.
One important step taken in the last couple years is “distributed quantum computing,” said Laszlo Gyongyosi, a researcher at Hungary’s Budapest University of Technology and Economics.
“Distributed quantum computing represents a new computing paradigm in which quantum processing tasks are spread across multiple quantum devices or nodes, thus allowing these devices to work collaboratively on complex problems,” he explained.
Because the qubits are managed across different locations or devices, it is now possible to do parallel processing of quantum algorithms. Combined with quantum entanglement, this allows systems to share computational resources, which improves the efficiency of the communications protocols and algorithms that power the quantum Internet.
In the last couple years, there have also been significant advances in quantum error correction techniques, quantum communication rates and distances, and the lifetime of quantum memories, according to Gyongyosi. “We expect significant improvements in the achievable quantum communication rates between quantum devices, quantum repeaters, and in the coherence times of quantum memories due to the developments of quantum technologies and quantum error correction techniques,” he said.
Due to those efficient error correction techniques, the percentage error of quantum gates in quantum devices has been reduced to a range of 0.01%. The achievable communication distances between quantum devices are now extendable via the integration of terrestrial and satellite quantum networking infrastructures. And the lifetime of a quantum memory has improved to the range of one hour.
“These are crucial for an experimental quantum Internet,” said Gyongyosi.
Practical Applications, Practical Problems
Today, the quantum Internet is mostly experimental. That is changing, however, thanks to quantum Internet’s promise for security.
Said Gyongyosi, “The development of the quantum Internet has already started both in theory and experiment, with a primary aim to provide unconditional security with advanced network services.
“The networked devices of the quantum Internet leverage quantum mechanics to establish communication networks, which can be used for applications involving security and privacy, remote sensing, or distributed computational capabilities, including the quantum cloud, quantum artificial intelligence, and solving computationally hard problems by means of limited-qubit computers.”
Gyongyosi expects actual applications for the quantum Internet to be implemented in practice in the next few years. That includes “quantum sensing,” or vastly improving the measurement of and interactions with the world by collecting data at the atomic level from individual atoms, rather than from huge collections of atoms as is currently done with classical systems.
“This allows quantum sensors to make our devices exponentially more accurate,” Gyongyosi said. This breakthrough could, in turn, lead to faster, more accurate, more reliable geolocation, medical diagnostics, and geographic imaging, to name just a few potential applications.
Liang Jiang, a professor in the Pritzker School of Molecular Engineering at the University of Chicago, agrees that practical applications for the quantum Internet are drawing near. A promising approach for “large-scale quantum networking” that will be developed in the coming years, he said, is the vacuum beam guide (VBG), which can enable quantum communication over distances of thousands of kilometers. “VBG offers quantum channel capacities exceeding 1013 qubits per second, orders of magnitude higher than those achievable through quantum satellite links,” Jiang said.
Yet despite the progress, it’s early and significant challenges remain. These include improving the accessibility of quantum services, automating the generation and deployment of quantum services, and simplifying the development and deployment of those services, said Gyongyosi, who added, “The importance of ensuring interoperability between devices from different manufacturers cannot be overemphasized.”
Jiang echoed that, saying that a major barrier is “Achieving entanglement generation over longer distances to enable global-scale connectivity and higher communication rates.”
Gyongyosi sees a future where, perhaps, the traditional and quantum Internets coexist.
“In the near future, the quantum Internet will exist in parallel with classical networks formulating hybrid high-performance quantum-classical networks,” he said. “The interoperability of classical and quantum services will remain an important focus area in a near-term setting.”
Logan Kugler is a freelance technology writer based in Tampa, FL. He is a regular contributor to CACM and has written for nearly 100 major publications.