Saturday, July 09, 2022

Record-setting quantum entanglement connects two atoms across 20 miles (33 kilometers) of telecom fiber cables

Amazing stuff! Over telecom fiber links!

"... In their experiments, the team entangled two rubidium atoms kept in optical traps in two different buildings on the LMU campus. They were separated by 700 m (2,297 ft) of fiber optics, which was extended out to 33 km with extra spools of cable. ... While photons have been entangled over great distances before, this study marks a new distance record for entangling two atoms ..."

From the abstract:
"Quantum networks promise to provide the infrastructure for many disruptive applications, such as efficient long-distance quantum communication and distributed quantum computing. ... recently, entanglement distribution has also been achieved over telecom fibres and analysed retrospectively. Yet, to fully use entanglement over long-distance quantum network links it is mandatory to know it is available at the nodes before the entangled state decays. Here we demonstrate heralded entanglement between two independently trapped single rubidium atoms generated over fibre links with a length up to 33 km. For this, we generate atom–photon entanglement in two nodes located in buildings 400 m line-of-sight apart and to overcome high-attenuation losses in the fibres convert the photons to telecom wavelength using polarization-preserving quantum frequency conversion. The long fibres guide the photons to a Bell-state measurement setup in which a successful photonic projection measurement heralds the entanglement of the atoms. Our results show the feasibility of entanglement distribution over telecom fibre links useful, for example, for device-independent quantum key distribution and quantum repeater protocols. The presented work represents an important step towards the realization of large-scale quantum network links."

Record-setting quantum entanglement connects two atoms across 20 miles

Quantenphysik: Rekordverschränkung von Quantenspeichern Forschende haben zwei Quantenspeicher über eine 33 Kilometer lange Glasfaserverbindung miteinander verschränkt – ein Rekord und ein wichtiger Schritt hin zum Quanteninternet.


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