The creation of a quantum internet is a long-term goal of several laboratories conducting experiments with quantum computers and quantum networks. The current internet lacks certain services and security measures that a quantum internet would offer.
This network of quantum computers, sensors, and communication devices would generate, process, and transmit entanglement and quantum states. It is expected that this network would improve society’s internet system.
By presenting a basic quantum network measurement that uses room-temperature quantum memory, a group of scientists from Stony Brook University and their partners have made a big leap toward constructing a quantum internet testbed. A publication in npj Quantum Information details their discoveries.
In order to convey information in an unhackable way and employ quantum mechanics to solve complicated problems considerably quicker than classical computing, the area of quantum information basically integrates parts of classical computing, mathematics, and physics.
A quantum internet prototype has not been constructed, despite the fact that the field has witnessed a dramatic rise in funding and a surge in interest from both researchers and the general public.
The research team from Stony Brook claims that creating systems that can transmit quantum information and entanglement across numerous nodes over long distances is the main obstacle to realizing the promise of more secure communication networks, more precise measurement systems, and more powerful algorithms for specific scientific analyses.
One of the more difficult problems in modern physics is understanding these systems, which are known as quantum repeaters. The most recent experiments show that the researchers’ quantum repeater capacities have increased.
In order to construct large-scale quantum repeater networks that will include several of these memories, it is crucial that these memories have similar performance, which they proved by building and characterizing room-temperature quantum memories.
They performed a classic test to measure the indistinguishability of photon properties, dubbed Hong-Ou-Mandel Interference, on the outputs from the memories and sent identical quantum states into each one to test how functionally identical these memories are.
Their room-temperature quantum memories can store and retrieve optical qubits without substantially altering the joint interference process. This opens the door to memory-assisted entanglement swapping, a protocol for dispersing entanglement over long distances, and the development of functional quantum repeaters.
Lead author Eden Figueroa, Ph.D., a Stony Brook Presidential Innovation Endowed Professor and Director of the Center for Distributed Quantum Processing with a joint appointment at the U.S. Department of Energy’s Brookhaven National Laboratory, expressed his belief that this is a remarkable advancement toward the creation of practical quantum repeaters and the quantum internet.
The team’s quantum technology is also extremely efficient and runs at room temperature, which drastically reduces operating costs and speeds up the system. Although it is more expensive, slower, and technically more difficult to network, most quantum research does not take place at room temperature but rather at temperatures close to absolute zero.
Hence, technology that operates at room temperature shows promise for constructing large-scale quantum networks. Their method has been patented, and they have achieved room temperature quantum memory and communication. A couple of their patents concern high-repetition-rate quantum repeaters and room-temperature quantum storage.
Any large-scale quantum internet must have the ability to bring together these quantum memory fleets in a room-temperature state that can work together at a quantum level. Figueroa stresses that their patented method allows them to further test the quantum network, and that to their knowledge, no one has ever shown this before. They plan to build on this study.
Joint writers Among Figueroa’s colleagues, postdoctoral researcher Sonali Gera and doctoral student Chase Wallace of the Physics and Astronomy Department collaborated on experiments that sought to “amplify” entanglement over distances, a key function of quantum repeaters.
“Because the memories are capable of storing photons with a user-defined storage time, we were also able to show time synchronization of the photons’ retrieval despite the photons arriving at the memories at random times, which is another feature necessary to operate a quantum repeater system,” according to Gera.
She and Wallace continue by saying that the team’s future plans include developing and studying entanglement sources that work with quantum memories and coming up with ways to “herald” the presence of stored photons in multiple quantum memories.
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