Improving gate fidelities for laser-written nitrogen vacancy centres in diamond membranes

如果量子计算机能够用足够多的量子比特建造，它将能够解决用我们现在拥有的经典计算机难以解决的问题。一种领先的设计是建立具有五个或更多相互作用的量子比特的节点，然后将这些节点中的许多连接起来。低温下金刚石中的氮空位中心(NVC)已经被用来通过光学纠缠它们的电子自旋来证明这种联系。与NVC耦合的核自旋可以有超过10秒的长相干时间。这个项目将利用我们的激光写入的NVC和我们可以围绕它们创建的激光写入的电线[1，2]。激光写作是由我们牛津大学的合作者帕特里克·索尔特团队完成的。我们将在钻石薄膜中建立这些量子比特的阵列，这样钻石就可以被放入牛津大学杰森·史密斯小组的光学腔中。我们将测量自旋相干时间，并提高自旋控制的保真度。最初的实验将在室温下进行，但也将使用低温测量，因为这是缠绕两个NVC所必需的。我们与Jason Smith在牛津的团队、Element Six和牛津仪器等离子体技术公司合作，作为英国国家量子计算和模拟(QCS)中心的一部分。这个博士生项目是由EPSRC通过这个中心资助的。

If a quantum computer could be built with enough qubits, it would be able to solve problems that are intractable with the classical computers we have now. A leading design for this is to build nodes with five or more interacting qubits, and then link up many of these nodes. Nitrogen vacancy centres (NVC) in diamond at cryogenic temperatures have been used to demonstrate this linking by entangling their electron spins optically. The nuclear spins coupled to NVC can have long coherence times of over 10 seconds. This project will make use of our laser-written NVC and the laser-written electrical wires we can create around them [1, 2]. The laser writing is done by the group of our collaborator Patrick Salter in Oxford University. We will build arrays of these qubits inside diamond membranes so that the diamonds can be put into optical cavities in the group of Jason Smith in Oxford. We will measure spin coherence times and improve the fidelity of the spin control. Initial experiments will be at room temperature, but cryogenic measurements will be used also as this is needed to entangle two NVC. We collaborate with Jason Smith's group in Oxford, Element Six and Oxford Instruments Plasma Technology as part of the UK National Quantum Computation and Simulation (QCS) Hub. This PhD studentship is funded by the EPSRC through this Hub.