Entangling dopant nuclear spins using double quantum dots

量子力学已经导致了对材料的电子和光学特性的深刻理解，这是过去一个世纪的技术革命的基础。然而，量子力学的关键要素，特别是“相干叠加”和“纠缠”等概念，仍然需要在技术应用中直接加以利用。随着我们控制越来越小的设备的能力不断提高，精度也越来越高，我们开始进入这样一个领域：这些概念可以从抽象的“思想实验”演变为真实设备所展示的现象。充分的控制、叠加和纠缠将使一套新的技术成为可能——被称为量子技术（QTs）——它对某些现有技术提供了重大和根本性的改进。例如，最终安全的通信，增强的传感器，以及能够解决当今任何现有计算机都难以解决的问题的“量子”计算机。硅器件已经证明了量子比特（qubit）的特性，这使得它们在未来的量子力学中非常有前途。对于大多数潜在的QT平台，下一个关键步骤是确定扩大控制和量子位之间相互作用的方法，并且，当比较不同的QT方法时，可以看到在使用“自然”量子系统（如基于原子的量子系统）和“人工”量子系统（如基于超导电路或量子点的量子系统）之间存在妥协。这个项目将把这两种方法结合在一起，在一个基于硅的架构中是可能的，以便从它们各自的优势中受益。我们将利用硅中供体自旋独特的长相干时间（可长达数小时），并对量子点进行可调控制，其中纠缠的单重态和三重态是自然基态。在此过程中，我们将展示一种可扩展的方法，在硅中纠缠非常长寿命的量子比特，这将使未来在计量和量子计算机中的应用成为可能。

Quantum mechanics has led to a deep and profound understanding of the electronic and optical properties materials, which has underpinned the technological revolution of the past century. Yet, there are key elements of quantum mechanics, specifically ideas such as 'coherent superposition' and 'entanglement', which have still to be harnessed directly in a technological application. With our improving ability to control smaller and smaller devices, with ever greater precision, we begin to enter a regime where such concepts can evolve from abstract 'thought experiments' to phenemona exhibited by real devices. Sufficiently controlled, superposition and entanglement will enable a new set of technologies - termed Quantum Technologies (QTs)- which offer major and fundamental improvements over certain existing technologies. Examples include ultimately secure communication, enhanced sensors, and 'quantum' computers able to solve problems that are simply intractable on any existing computer today. Silicon devices have demonstrated quantum bit (qubit) characteristics which make them extremely promising for future QTs. As for most potential QT platforms, the next key step is identifying ways to scale up control and interactions between qubits, and, as seen when comparing different QT approaches, there is a compromise between using 'natural' quantum systems such as those based on atoms, and 'artificial' ones such as those based on superconducting circuits or quantum dots. This project will bring together both such approaches, as is possible within a silicon-based architecture, in order to benefit from their respective advantages. We will use the uniquely long coherence times of donor spins in silicon (which can be as long as hours), with the tunable control of quantum dots in which entangled singlet and triplets are natural basis states. In doing so, we will demonstrate a scalable method to entangle very long-lived quantum bits in silicon, which will enable future applications in metrology and quantum computers.