Evrim Yazgin
Cosmos science journalist
If quantum computers are to fulfill the promise of solving problems faster or which are too complex for classical supercomputers, then quantum information needs to be communicated between multiple processors.
Modern computers have different interconnected components such as a memory chip, a Central Processing Unit and a General Processing Unit. These need to communicate for a computer to function.
Current attempts to interconnect superconducting quantum processors use “point-to-point” connectivity. This means they require a series of transfers between nodes, compounding errors.
A new device described in a paper published in Nature Physics replaces “point-to-point” connectivity with “all-to-all” in a bid to overcome these issues. The aim is to allow all superconducting quantum processors in a network to communicate directly with each other.
“In the future, a quantum computer will probably need both local and nonlocal interconnects,” says lead author Aziza Almanakly, an electrical engineering and computer science graduate student at the Massachusetts Institute of Technology (MIT).
“Local interconnects are natural in arrays of superconducting qubits. Ours allows for more nonlocal connections.”
The device includes a superconducting waveguide to direct photons carrying quantum information between processors.
The team demonstrated remote entanglement, enabling a correlation between quantum processors that aren’t physically connected.
“We can send photons at different frequencies, times, and in 2 propagation directions, which gives our network more flexibility and throughput,” Almanakly adds.
“Generating remote entanglement is a crucial step toward building a large-scale quantum processor from smaller-scale modules,” explains co-author Beatriz Yankelevich. “Even after that photon is gone, we have a correlation between two distant, or ‘nonlocal,’ qubits. Remote entanglement allows us to take advantage of these correlations and perform parallel operations between 2 qubits, even though they are no longer connected and may be far apart.”
“We can use this architecture to create a network with all-to-all connectivity. This means we can have multiple modules, all along the same bus, and we can create remote entanglement among any pair of our choosing,” Yankelevich says.
“In principle, our remote entanglement generation protocol can also be expanded to other kinds of quantum computers and bigger quantum internet systems,” Almanakly adds.
