Long-term transmission of entangled photons from a single quantum dot over deployed fiber

Zi-Heng Xiang,Jan Huwer,Joanna Skiba-Szymanska,Andrew J Shields,Ian Farrer,R Mark Stevenson,Martin B Ward,David A Ritchie

doi:10.1038/s41598-019-40912-z

Zi-Heng Xiang, Jan Huwer + Show 6 more

Open Access

https://doi.org/10.1038/s41598-019-40912-z

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Abstract

Entangled light sources are considered as core technology for multiple quantum network architectures. Of particular interest are sources that are based on a single quantum system as these offer intrinsic security due to the sub-Poissonian nature of the photon emission process. This is important for applications in quantum communication where multi-pair emission generally compromises performance. A large variety of sources has been developed, but the generated photons remained far from being utilized in established standard fiber networks, mainly due to lack of compatibility with telecommunication wavelengths. In this regard, single semiconductor quantum dots are highly promising photon pair sources as they can be engineered for direct emission at telecom wavelengths. In this work we demonstrate the feasibility of this approach. We report a week-long transmission of polarization-entangled photons from a single InAs/GaAs quantum dot over a metropolitan network fiber. The photons are in the telecommunication O-band, favored for fiber optical communication. We employ a polarization stabilization system overcoming changes of birefringence introduced by 18.23 km of installed fiber. Stable transmission of polarization-encoded entanglement with a high fidelity of 91% is achieved, facilitating the operation of sub-Poissonian quantum light sources over existing fiber networks.

Highlights

With the number of emerging quantum technologies rapidly increasing, the development of quantum networks is becoming more important than ever
Sub-Poissonian photon pair sources based on a single quantum emitter such as semiconductor quantum dots (QD) are a promising alternative, as they provide intrinsic security against photon number splitting attacks
Quantum states being encoded in the photon polarization are naturally favored for qubit generation in sources being based on single quantum emitters[15,16,17,18,19], as they can directly interface with electronic states on optical dipole transitions

Summary

Introduction

With the number of emerging quantum technologies rapidly increasing, the development of quantum networks is becoming more important than ever. Quantum states being encoded in the photon polarization are naturally favored for qubit generation in sources being based on single quantum emitters[15,16,17,18,19], as they can directly interface with electronic states on optical dipole transitions. For long-distance transmission over optical fiber, polarization qubits are affected by random drifts in birefringence due to changing environmental conditions.

Results

Conclusion