Xiang, Z., Huwer, J., Skiba-Szymanska, J. et al. A tuneable telecom wavelength entangled light emitting diode deployed in an installed fibre network. Commun Phys 3, 121 (2020). https://doi.org/10.1038/s42005-020-0390-7
Entangled light emitting diodes based on semiconductor quantum dots are promising devices for security sensitive quantum network applications, thanks to their natural lack of multi photon-pair generation. Apart from telecom wavelength emission, network integrability of these sources ideally requires electrical operation for deployment in compact systems in the field. For multiplexing of entangled photons with classical data traffic, emission in the telecom O-band and tuneability to the nearest wavelength channel in compliance with coarse wavelength division multiplexing standards (20 nm channel spacing) is highly desirable. Here we show a fully electrically operated telecom entangled light emitting diode with wavelength tuneability of more than 25 nm, deployed in an installed fibre network. With the source tuned to 1310.00 nm, we demonstrate multiplexing of true single entangled photons with classical data traffic and achieve entanglement fidelities above 94% on an installed fibre in a city.