Theory and experiments have shown that future quantum computers will harness the peculiar properties of quantum mechanics to go above and beyond what is currently possible with even the most powerful supercomputers.
These quantum computers will communicate through the quantum internet, which is not as easy as plugging them into the phone line. One crucial requirement in quantum computing is that the particles that perform the calculations are entangled, a quantum mechanical phenomenon where they become part of a single state. A change to one of the particles creates instantaneous changes to the others no matter how far apart they are.
These entangled states are easily disrupted, unfortunately. So how can they be sent between computers to communicate? That’s where quantum teleportation comes in. The entangled state is transferred between two particles. This technique is not perfectly efficient, and scientists are working hard in trying to make the whole process more successful.
A team of researchers from multiple organizations has reported a record-breaking achievement in PRX Quantum. They were able to deliver sustained, long-distance teleportation of qubits (quantum bits) with a fidelity greater than 90% over a fiber-optic network distance of 44 kilometers (27 miles).
“We’re thrilled by these results,” co-author Panagiotis Spentzouris, head of the Fermilab quantum science program, said in a statement. “This is a key achievement on the way to building a technology that will redefine how we conduct global communication.”
Quantum teleportation doesn’t work like the science fiction popularization of teleportation. What you are teleporting is the state of particles via a quantum channel and a classical channel. The sender has the original qubit. This is made to interact with one particle in an entangled pair, producing “classical signal” information about the state of the original qubit. This signal and the other half of that entangled pair are sent to the receiver, and by putting it together, the receiver can recreate the original qubit.
This success is the result of a collaboration between Fermilab, AT&T, Caltech, Harvard University, NASA Jet Propulsion Laboratory, and the University of Calgary. The systems on which this quantum teleportation was achieved were created by Caltech’s public-private research program on Intelligent Quantum Networks and Technologies, or IN-Q-NET.
“We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems,” explained Maria Spiropulu, the Shang-Yi Ch’en professor of physics at Caltech and director of the IN-Q-NET research program. “The results will be further improved with system upgrades we are expecting to complete by the second quarter of 2021.”
Quantum computers are not here yet, but having the infrastructure to make them work is crucial. The U.S. Department of Energy published its roadmap for a national quantum internet, last July.