Demonstration of Quantum Memory at Telecom Wavelengths
A collaboration of researches from the Imperial College London, the University of Stuttgart, the Julius Maximilian University of Würzburg and the University of Southampton succeeded in demonstrating writing to and reading from a quantum memory. The used photons were created in a single-photon source based on a quantum dot and have a wavelength typically used in telecommunication .
While photons are well suited to transport quantum informationen, it is difficult to retain them. Furthermore quantum states are very fragile and transmission over fibre is not possible beyond distances of a few hundred kilometers. If it is possible to reliably retain photons, one could construct so-called quantum repeaters that can increase the transmission distance using a method called Entanglement-Swapping. Therefore the demonstration of writing to and reading from a quantum memory in a commonly used wavelength regime represents an important step. However the currently achievable memory efficiency is only ~13% and therefore still requires strong improvements from future developments.
More details about this demonstration can be found in the press release of the Imperial College London and the associated publication https://doi.org/10.1126/sciadv.adi7346.
More information about quantum networks, quantum repeaters and Entanglement-Swapping are also available on the website of the WiN-Lab.