Dopant-based Quantum Technologies in Silicon

量子技术在过去十年中取得了长足的发展，现在有几种材料平台可以运行少量的量子位;例如基于捕获离子，超导或半导体材料的平台。其中，目前最有前途的量子位实现之一是硅中的掺杂剂自旋。硅中电子和核自旋的相干时间通常分别超过毫秒和秒。与此同时，硅平台受益于能够建立在半导体行业的专业知识和制造设施。尽管如此，使用半导体材料作为固态量子位的平台也面临着独特的挑战，甚至与最先进的经典硅技术也不同。例如，与在经典电子学中发现的半导体芯片不同，自旋量子比特即使对最小的磁场波动也敏感，对经由自旋-电荷耦合路径（诸如自旋-轨道或交换耦合）的电荷波动敏感，并且通常需要在低温下操作。要将硅中的掺杂剂自旋开发成一种可行的、可扩展的技术，使社会受益，仍然需要学术界和行业合作伙伴的一些步骤变化和持续投资。在这里，我们将汇集来自英国和海外大学的人才，以及许多行业合作者，他们是解决这些挑战的唯一合适人选。在我们的人才网络带来的关键能力中，第一个是制造原子精度掺杂剂器件（UCL）的能力。在国际上，拥有这种专业知识的团队很少，在某些方面，例如在硅中掺入As掺杂剂，我们的专业知识确实是独一无二的。为了评估这些设备，需要mK传输测量来建立关键指标，如量子相干性和门相干性。在这里，我们汇集了几个小组（伦敦大学学院，悉尼），他们在这方面有很长的记录，以及在基准测试和量子纠错方面所需的理论基础（悉尼，麦吉尔）。尽管如此，为了充分理解器件性能，必须理解并从字面上绘制出量子器件的性能，其能量和空间分辨率是任何传统技术都不可能实现的。在我们的网络中，我们有能力联合收割机的传输测量与mK扫描门映射的设备（剑桥）和单电子灵敏度的纳米尺度（麦吉尔）。这项工作将分为两个工作包，第一个工作包侧重于构建所需的量子位制造和设备结构，而第二个工作包将专注于在物理上分离的量子比特之间产生纠缠。将这些关键能力和研究成果结合到一个单一的网络中，使我们能够在量子器件开发和表征方面大大超越当前的技术水平，并且可以制造可行的原型。除了第一个原型，该网络还将致力于平台的可扩展性，包括设备制造（UCL）和所需的经典低温控制电子设备（悉尼）。另一个好处是，研究小组与工业领导者在数据采集，材料表征以及硬件和软件开发方面紧密结合。为了确保我们的研究将达到广泛的受众，并提供给所有相关的利益相关者，我们将有一个专门的推广计划（悉尼牵头）。

Quantum technologies have seen considerable development over the last decade and there are now several material platforms available in which a small number of qubits can be operated; such as those based on trapped ions, superconducting, or semiconductor materials. Of these, one of the most promising current qubit implementations are dopant spins in silicon. The coherent times of electron and nuclear spins in silicon routinely exceeds milliseconds and seconds, respectively. At the same time, the silicon platform benefits from being able to build on the expertise and fabrication facilities of the semiconductor industry. Nevertheless, using semiconductor materials as a platform for solid-state qubits comes with its own unique challenges that are different from even state-of-the art-classical silicon technology. For example, unlike semiconductor chips found in classical electronics, spin qubits are susceptible to even the smallest magnetic field fluctuations, are sensitive to charge fluctuations via spin-to-charge coupling pathways such as spin-orbit or exchange coupling, and typically require operation at cryogenic temperatures. To develop dopant spins in silicon into a viable and scalable technology that would benefit society still requires a number of step changes and sustained investment from academic and industry partners. Here, we will therefore bring together a network of people from both UK and overseas universities, as well as many industry collaborators, which are uniquely suited to address these challenges.Of the key capabilities that our network of people brings, the first is the ability to fabricate dopant devices with atomic precision (UCL). Internationally there are very few groups with this expertise, and in some aspects, such as the incorporation of As dopants in silicon, our expertise is truly unique. To assess the devices requires mK transport measurements to establish key metrics such as quantum coherence and gate fidelities. Here we bring together several groups (UCL, Sydney) which have a long track record in this regard, as well as the required theoretical underpinning in terms of benchmarking and quantum error correction (Sydney, McGill). Still, for a full understanding of the device performance it is essential to understand and, quite literally, map out the performance of the quantum devices with energy and spatial resolution not possible with any conventional technology. In our network, we have the capability to combine the transport measurements with mK scanning gate mapping of the device (Cambridge) and single-electron sensitivity on the nm scale (McGill). The work will be brought together in two work packages, the first focussing on building the required qubit fabrication and device structures, whereas the second work package will focus on creating entanglement between physically separated qubit.Combining these key capabilities and research efforts into a single network allows us to go significantly beyond the current state of the art in terms of quantum device development and characterisation such that reliable and viable prototypes can be built. Looking beyond the first prototypes the network will also be working on the scalability of the platform, both in terms of device fabrication (UCL) and the required - classical cryogenic - control electronics (Sydney). An additional benefit is that the research group is strongly integrated with industrial leaders, in terms of data acquisition, materials characterisation and hardware and software development. To ensure our research will reach a wide audience and be available to all relevant stakeholders we will have a dedicated outreach programme (Sydney lead).