Erste Demonstration der Quantenteleportation über ein Glasfaserkabel, das bereits Internetverkehr überträgt. Advance öffnet die Tür für sichere Quantenanwendungen ohne spezielle Infrastruktur.

**Quantum teleportation coexisting with classical communications in optical fiber**

Abstract

The ability for quantum and conventional networks to operate in the same optical fibers would aid the deployment of quantum network technology on a large scale. Quantum teleportation is a fundamental operation in quantum networking, but has yet to be demonstrated in fibers populated with high-power conventional optical signals. Here we report, to the best of our knowledge, the first demonstration of quantum teleportation over fibers carrying conventional telecommunications traffic. Quantum state transfer is achieved over a 30.2-km fiber carrying 400-Gbps C-band classical traffic with a Bell state measurement performed at the fiber’s midpoint. To protect quantum fidelity from spontaneous Raman scattering noise, we use optimal O-band quantum channels, narrow spectro-temporal filtering, and multi-photon coincidence detection. Fidelity is shown to be well maintained with an elevated C-band launch power of 18.7 dBm for the single-channel 400-Gbps signal, which we project could support multiple classical channels totaling many terabits/s aggregate data rates. These results show the feasibility of advanced quantum and classical network applications operating within a unified fiber infrastructure.

[https://opg.optica.org/optica/fulltext.cfm?uri=optica-11-12-1700](https://opg.optica.org/optica/fulltext.cfm?uri=optica-11-12-1700)