A solid-state source of strongly entangled photon pairs with high brightness and indistinguishability
Jin Liu, Rongbin Su, Yuming Wei, Beimeng Yao, Saimon Filipe Covre da Silva, Ying Yu, Jake Iles-Smith, Kartik A. Srinivasan, Armando Rastelli, Juntao Li, Xuehua Wang
The generation of high-quality entangled photon pairs has been being a long-sought goal in modern quan-tum communication and computation. To date, the most widely-used entangled photon pairs are gener-ated from spontaneous parametric downconversion, a process that is intrinsically probabilistic and thus relegated to a regime of low pair-generation rates. In contrast, semiconductor quantum dots can gen-erate triggered entangled photon pairs via a cascaded radiative decay process, and do not suffer from any fundamental trade-off between source brightness and multi-pair generation. However, a source fea-turing simultaneously high photon-extraction efficiency, high-degree of entanglement fidelity and photon indistinguishability has not yet been reported. Here, we present an entangled photon pair source with high brightness and indistinguishability by deterministically embedding GaAs quantum dots in broad-band photonic nanostructures that enable Purcell-enhanced emission. Our source produces entangled photon pairs with a record pair collection probability of up to 0.65(4) (single-photon extraction efficiency of 0.85(3)), entanglement fidelity of 0.88(2), and indistinguishabilities of 0.901(3) and 0.903(3), which im-mediately creates opportunities for advancing quantum photonic technologies.