Memory-Enhanced Entanglement Distribution with Gallium ARsenide quantum Dots

利用光子和物质的量子特性传输数据的通信网络从根本上比传统网络更安全，将成为即将到来的量子信息处理时代不可或缺的一部分。这种量子网络的基本组成部分是一个节点，在这个节点上，飞行的光子量子比特和静止的物质量子比特可以高效且高保真地交换信息。尽管存在多个潜在的平台，但半导体量子点(QD)由于其光学性质而脱颖而出：它们是固态中最明亮和最相干的量子发射体。申请人最近提出的量子点中电子和核自旋相干性的显著改进进一步加强了将该系统作为协同努力的焦点的理由，以实现能够进行全硬件堆栈演示的设备。我们建议结合多个研究小组的专业知识和互补的技能和焦点来实现一体式设备交付：一个能够在物质量子比特和光子量子比特之间产生纠缠并以90%的保真度存储该信息100毫秒的半导体QD系统，比以前的基于QD的结果提高了105%。我们将通过量身定制和理论指导的量子点生长和生长后控制来实现这一点，以优化光学和自旋性质，我们将在光谱测量中进行验证。我们将把这样的QD设备与(1)应变工程平台--允许调谐电子自旋量子比特和核寄存器之间的相互作用；(2)光学微腔--允许高效的光子耦合；以及(3)射频天线--允许动态地去耦合核自旋寄存器100毫秒。我们联盟的每个学术成员都单独或在双边/三方非正式合作中就上述基本要素取得了多项成果；该项目将提供资源，将成员聚集在一起，并利用他们现有的资源来产生独特和高度影响的量子设备演示。一个在晶片规模异质集成方面拥有专业知识的工业合作伙伴将为可扩展制造工艺的开发做出贡献。MEEDGARD的成功将对未来基于半导体的量子网络投资产生直接影响。

Communication networks that use the quantum properties of photons and matter for transferring data are fundamentally more secure than traditional networks and will become indispensable in the coming era of quantum information processing. The fundamental building block for such a quantum network is a node where flying photonic qubits and stationary matter qubits can exchange information efficiently and with high fidelity. While multiple prospective platforms exist, semiconductor quantum dots (QDs) stand out owing to their optical properties: they are the brightest and most coherent quantum emitters in the solid-state. Remarkable improvements of electronic- and nuclear-spin coherence in QDs recently put forward by the applicants have further strengthened the case for placing this system as the focus of a concerted effort towards a device capable of a full hardware stack demonstration.We propose to combine the expertise of multiple research groups with complementary skills and foci to achieve an all-in-one device delivery: a semiconductor QD system capable of producing entanglement between a matter qubit and a photonic qubit and storing this information with 90% fidelity for 100 milliseconds, a 105 improvement over previous QD-based results. We will deliver this with tailored and theory-guided QD growth and post-growth control to optimise optical and spin properties, which we will verify in spectroscopic measurements. We will integrate such a QD device with (1) a strain-engineering platform - allowing tuning of the interaction between an electron spin qubit and a nuclear register; (2) an optical micro-cavity - allowing efficient photon coupling; and (3) radiofrequency antennas - allowing dynamical decoupling of the nuclear spin register for 100 ms. Each academic member of our consortium has produced multiple results on the above foundational elements either separately or within bi-/tri-lateral informal collaborations; this project will provide the resources to bring members together and leverage their existing resources to produce a unique and highly impactful quantum device demonstration. An industrial partner, with expertise on wafer-scale heterogeneous integration, will contribute to the development of scalable fabrication processes. MEEDGARD's success would have direct ramifications for future investment in semiconductor-based quantum networking.