Utilising novel microwave filtering techniques for improved performance in superconducting quantum devices

即将到来的量子计算技术革命给工程师带来了一些令人兴奋的挑战，也给现有公司和初创企业带来了同样令人兴奋的商机。其中一个挑战是，现有的超导量子计算机已经被密集的布线和笨重的微波组件所拥挤，稀释冰箱的物理空间有限。移动到100-1000量子位及更高的水平需要可扩展和经济高效的微波控制和测量电路的新解决方案。简单地说，微波控制系统需要比目前更轻的重量和更小的物理尺寸，同时具有高水平的集成度，同时具有成本效益和能源效率。一些关键需要的低温微波控制组件是密集布线、衰减器和循环器，它们用于将控制信号从电子设备引入低温恒温器，以允许传输所需的频段，同时拒绝不需要的频段，并保护量子处理器免受反射信号和退相干的影响。通常，密集的布线连接、滤波器和循环器在低温恒温器中占据相当大的尺寸，并且随着我们扩大量子位的数量，所需的数量也在迅速增长。例如，为了扩展到100万量子位计算机，控制系统还需要1- 1000万个滤波器、环行器和同轴电缆，占用超过三个足球场的面积，消耗大约40兆瓦的直流功率（假设没有与信号分布相关的功率损耗）。为超导量子计算开发微型、低成本、可靠、插入损耗和高度集成的微波技术对于英国在这个快速增长的领域取得成功至关重要，预计到2024年全球市场将达到40亿英镑。为了达到100量子位及以上的水平，量子计算变得真正有用，需要创新可扩展的微波控制系统。英国有一个很短的时间窗口，可以投资于超导量子计算的实际演示。如果没有这一点，英国研究人员在这一新兴领域领导世界、建立强大的学术和工业领导力的潜力将会丧失。我的奖学金旨在将现代微波方法引入超导量子计算，并在降低硬件开销和热负载的情况下展示改进的量子性能，为迈向100量子比特水平铺平道路，量子计算在那里变得真正有用

The coming revolution in quantum computing technologies creates some exciting challenges for engineers and equally exciting business opportunities for existing companies and new start-ups. One of these challenges is that existing superconducting quantum computers are already overcrowded with dense wiring and bulky microwave components, there is simply limited physical space in the dilution refrigerators. Moving to the 100-1000-qubit level and beyond requires new solutions for scalable and cost-effective microwave control and measurement circuity. Simply put, the microwave control systems need to be of much lighter weight and smaller physical size than at present with a high level of integration while being cost-effective and energy efficient.Some of the critically required cryogenic microwave control components are dense wiring, attenuators, and circulators, which are used to bring control signals from the electronics into the cryostat, to allow the transmission of desired frequency bands while rejecting unwanted bands and to protect quantum processors against reflected signals and decoherence. Typically, dense wiring connections, filters and circulators occupy quite a large size in the cryostat and the number of them needed is growing rapidly as we scale up the number of qubits. For example, in order to scale to 1-million-qubit-computer, the control system would also need 1-10 million filters, circulators, and coaxial cables, occupying more than three football fields of floor space and consume roughly 40 MW of dc power (assuming no power loss associated with signal distribution). It is vital to develop miniature, low-cost, reliable, insertion loss and highly integrated microwave technologies for superconducting quantum computing for the UK to be successful in this rapidly growing sector, with a projected global market of £4B by 2024.In order to move to the 100s-qubit level and beyond, where quantum computing becomes truly useful, innovation for scalable microwave control systems is needed. A short time-window is available for the UK to invest in real-world demonstration of superconducting quantum computing. Without this, the potential for a UK researcher to lead the world in this emerging area and build strong academic and industrially facing leadership will be lost. My fellowship aims to bring modern microwave approaches to supercondcting quantum computing and demonstrate improved quantum pefromance with reduced hardware overheads and thermal loaads, paving the way to move towards 100s-qubit level, where quantum computing becomes truly useful