Entangling dopant nuclear spins using double quantum dots

量子力学使人们对材料的电子和光学性质有了深刻而深刻的理解，从而支撑了过去世纪的技术革命。然而，量子力学的一些关键要素，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，精确度越来越高，我们开始进入这样一种状态，在这种状态下，这些概念可以从抽象的“思想实验”演变为真实的设备所展示的现象。充分控制，叠加和纠缠将使一套新的技术-称为量子技术（QTs）-提供了对某些现有技术的重大和根本性的改进。例如，最终安全的通信，增强的传感器和“量子”计算机能够解决当今任何现有计算机都无法解决的问题。硅器件已经表现出量子比特（qubit）特性，这使得它们在未来的量子点中极具前景。对于大多数潜在的QT平台来说，下一个关键步骤是确定扩大量子位之间的控制和相互作用的方法，并且，正如在比较不同的QT方法时所看到的那样，在使用“自然”量子系统（例如基于原子的系统）和“人造”量子系统（例如基于超导电路或量子点的系统）之间存在一个妥协。该项目将把这两种方法结合在一起，因为在基于硅的架构中是可能的，以便从它们各自的优势中受益。我们将使用硅中施主自旋的独特的长相干时间（可以长达几个小时），以及量子点的可调控制，其中纠缠的单线态和三线态是自然的基态。在这样做的过程中，我们将展示一种可扩展的方法来纠缠硅中寿命很长的量子比特，这将使未来的计量学和量子计算机的应用成为可能。

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.