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Coherent light scattering from a telecom C-band quantum dot.

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Wells, L 
Stevenson, RM 
Skiba-Szymanska, J 


Quantum networks have the potential to transform secure communication via quantum key distribution and enable novel concepts in distributed quantum computing and sensing. Coherent quantum light generation at telecom wavelengths is fundamental for fibre-based network implementations, but Fourier-limited emission and subnatural linewidth photons have so far only been reported from systems operating in the visible to near-infrared wavelength range. Here, we use InAs/InP quantum dots to demonstrate photons with coherence times much longer than the Fourier limit at telecom wavelength via elastic scattering of excitation laser photons. Further, we show that even the inelastically scattered photons have coherence times within the error bars of the Fourier limit. Finally, we make direct use of the minimal attenuation in fibre for these photons by measuring two-photon interference after 25 km of fibre, demonstrating finite interference visibility for photons emitted about 100,000 excitation cycles apart.


Acknowledgements: The authors gratefully acknowledge the usage of wafer material developed during earlier projects in partnership with Andrey Krysa and Jon Heffernan at the National Epitaxy Facility and at the University of Sheffield. They further acknowledge funding from the Ministry of Internal Affairs and Communications, Japan, via the project ‘Research and Development for Building a Global Quantum Cryptography Communication Network’. L.W. gratefully acknowledges funding from the EPSRC and financial support from Toshiba Europe Limited.

Funder: Ministry of Internal Affairs and Communications, Japan. Project 'Research and Development for Building a Global Quantum Cryptography Communication Network'


5108 Quantum Physics, 40 Engineering, 4009 Electronics, Sensors and Digital Hardware, 51 Physical Sciences, 5102 Atomic, Molecular and Optical Physics

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Nat Commun

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Springer Science and Business Media LLC