Semiconductor-generated entangled photons for hybrid quantum networks

Keiichi Edamatsu

Mattia Beccaceci, Giuseppe Ronco, Fabrizio Cienzo +16 more

Entanglement swapping is a protocol that details how to create entanglement between previously uncorrelated particles. Its all-photonic version - mediated by the interference of photon pairs generated by separate quantum systems-finds disparate applications in quantum networks. So far, all-photonic entanglement swapping between remote systems has been implemented only using sources that operate probabilistically. However, the scaling up of quantum networks requires deterministic quantum emitters that do not suffer from a trade-off between degree of entanglement and photonpair generation rate. Here, we demonstrate all-photonic entanglement swapping using photon-pairs generated by two separate GaAs quantum dots. The emitters are deterministically embedded in hybrid semiconductor-piezoelectric devices that make the entangled-photons from two dissimilar quantum dots nearly identical. Entanglement swapping is demonstrated with a fidelity as high as 0.71(2), more than 10 standard deviations above the classical limit. The experimental data are quantitatively explained by a theoretical model that also suggests how to boost the protocol performances. Our work opens the path to the exploitation of quantum dot entangled-photon sources in quantum repeater networks.

Hua Wei, Tingting Zeng, Ranran Fang

A hybrid quantum networks made of single-charged quantum dots and cavities, connected by fibers between cavity nodes, is illustrated. We show that how the state of quantum dot is manipulated by single photons, its functions in optical transport and phase control and thereafter its applications in quantum information transfer and entanglement generation. We give the dynamics of the system governed by the basic input-output equations for the cavity and single photons, and the corresponding numerical simulation.

Yannick Strocka, Fenglei Gu, Gregor Pieplow +2 more

We propose and analyze a hybrid quantum repeater architecture that combines two leading hardware platforms: quantum dots (QDs) as bright, deterministic sources of entangled photon pairs and group-IV-vacancy centers in diamond as efficient, heralded quantum memories. This combination leverages high-rate entanglement generation together with long-lived storage, enabling scalable entanglement distribution over long distances. A key challenge is the large bandwidth mismatch between QD photons and the narrow optical transitions of the memories. We combine a comprehensive model of the spin-photon interface, including full spin-photon coupling dynamics, and explore mitigation strategies such as frequency filtering and optimized magnetic-field orientation. Our results show that with optimized designs, photon-to-memory transfer can be achieved with high efficiency and fidelity, supporting the feasibility of such hybrid systems. Finally, we analyze a full repeater chain using experimentally achievable parameters and find that a network with thousands of memories across several repeater nodes could achieve a secret-key rate of 500 bit/s over 1,000 km, demonstrating the strong potential of this approach for next-generation quantum networks.

Keiichi Edamatsu, Goro Oohata, Ryōsuke Shimizu +1 more

Andrew J. Shields, R. M. Stevenson, Robert James Young