Researchers from LMU and Saarland University have entangled two quantum memories over a 33-kilometer-long fiber optic connection — a record and an important step toward the Quantum Internet.
This is the longest distance so far that anyone has ever managed entanglement via a telecom fiber. The quantum mechanical entanglement is mediated via photons emitted by the two quantum memories. A decisive step was the researchers’ shifting of the wavelength of the emitted light particles to a value that is used for conventional telecommunications.
For their experiment, the researchers use a system comprised of two optically trapped rubidium atoms in two laboratories on the LMU campus. The two locations are connected via a 700-meter-long fiber optic cable, which runs underneath Geschwister Scholl Square in front of the main building of the university. By adding extra fibers on coils, connections of up to 33 kilometers in length can be achieved.
The paper has been published in Nature.
