Microfabricated Ion-Cavity nodes for Robust, Optically-Networked Quantum Computing (MICRON-QC)

量子计算即将改变我们解决人类最困难的计算问题的方式，但尽管最近在量子比特控制和纠错码设计方面取得了进展，没有一个量子比特平台令人信服地展示了一条自由可伸缩的途径。在所有平台中，囚禁离子保持了高保真量子比特操作的记录，并实现了高度连接的体系结构，大大减少了大型设备的门数量。然而，单个单片处理器上量子比特数的可伸缩性预计将远远低于有用的容错计算所需的上限，而实现可伸缩性的最终途径在于将量子计算机分布在由较小处理器组成的网络中。该项目将构建并运行第一个可重构的囚禁离子处理器网络，该网络由通过光纤互连发射的单个光子连接，最终由5个节点组成。我将展示有效的大规模网络计算所需的所有元素，包括：适合高保真远程传输的飞行量子比特编码和波长；能够实现任意节点到任意节点的连接和并行多个节点对的纠缠的可重新配置的光子网络；以及每个节点中有足够的量子比特资源，允许在网络中组装任意纠缠的图态。我将在每个节点上构建基于腔的网络接口，能够以1 MHz的尝试速率近乎确定的离子-光子纠缠，允许以100 kHz的速率远程创建离子-离子纠缠，接近本地门的速率。通过明智的协议设计和先进的微系统工程相结合，我将展示这一点可以通过非常简单和健壮的构造的节点来实现，从而实现近乎自主的操作。虽然5节点网络将实现许多引人入胜的实验，但该项目的主要目标将是证明数百或数千个节点的网络是触手可及的。

Quantum computing is poised to transform the way we tackle humanity's hardest computational problems, but despite recent progress in qubit control and error-correcting code design, no qubit platform has convincingly demonstrated a route to free scalability. Of all platforms, trapped ions retain the record for high-fidelity qubit operations, and enable highly-connected architectures, greatly reducing gate-count for large devices. However, scaling of qubit numbers on a single, monolithic processor is expected to hit a ceiling far below that required for useful fault-tolerant computation, and the ultimate route to scalability lies in distributing the quantum computer across a network of smaller processors.This project will construct and operate the first reconfigurable network of trapped ion processors linked by single photons emitted over fibre interconnects, ultimately consisting of 5 nodes. I will demonstrate all the elements required for efficient large-scale networked computation including: a flying qubit encoding and wavelength suitable for high-fidelity long-range transmission; a reconfigurable photonic network enabling any-to-any node connectivity and entanglement of multiple node-pairs in parallel; and sufficient qubit resource within each node to permit the assembly of arbitrary entangled graph states across the network. I will construct cavity-based network interfaces at each node capable of near-deterministic ion-photon entanglement at 1MHz attempt rates, allowing remote ion-ion entanglement creation at 100kHz rates, close to those of local gates. Through a combination of informed protocol design and advanced microsystem engineering, I will demonstrate that this can be achieved with nodes of remarkably simple and robust construction, enabling near-autonomous operation. While the 5-node network will enable many fascinating experiments, the principal objective of the project will be to prove that a network of hundreds or thousands of nodes is within reach.