On-Chip milliKelvin Electronic Refrigerator for Astronomical and Quantum Device Applications

我们打算开发一种新的用户友好技术，使小型设备能够冷却到极低的温度（<100mk）。这样的能力将允许多样化和未来的应用蓬勃发展。其中包括黑洞探测、癌症探测和量子计算。我们建议通过使用电子冷却过程来实现这一点，其中相对高能（热）载流子（电子或空穴）量子力学地从介质中隧穿出来，从而导致介质中的平均电子温度降低。将这种工艺应用于实现极低温度是非常新的，我们希望通过在电子冷却器的设计中引入新一代半导体SiGe来大大提高其效率，并与之一起，发展良好的硅加工技术-因此，最终，这种冷却器可以经济地生产并达到工业标准。冷却器将被制造在一个小硅芯片的外围，热链接到安装在芯片中心的有源设备（有效载荷）。这需要非常好的散热设计，这样电子冷却器就能有效地冷却有效载荷。然而，在某些情况下，只需要冷却电子/不需要冷却晶格原子；SiGe在控制电子和晶格之间的热耦合方面具有很大的灵活性。这种电子冷却器可以在0.3K的起始温度下工作，该温度可以由低温无流体闭式循环氦低温恒温器产生，因此可以设想一种开关技术，可以进入~10mK的工作环境。这将是一项巨大的技术进步，因为现有的技术需要大量复杂的低温流体设备。在项目的第一阶段，我们将研究几种实现有效电子冷却的方法，利用SiGe及其相关金属硅化物在极低温度下可以获得的广泛的基本电子条件，从而增强载流子输运和热电效应。新的冷却器将在两个备受关注的领域进行测试，即辐射探测器和量子信息设备。它们可以极大地提高我们探测的能力，例如，探测从最早的黑洞发出的光子，用卫星探测器工作在100mK以下。而且，非常重要的是，这种检测器可以彻底改变在生物医学研究中广泛使用的荧光检测，使我们对基于基因的疾病（例如癌症）和单细胞工作的理解取得进展。此外，量子计算时代要求量子比特设备以10-20mK的速度运行，这确实令人敬畏。华威大学正在协调该项目，并组建了一个由来自英国四所大学（华威大学、卡迪夫大学、莱斯特大学和伦敦大学（皇家霍洛威大学））和四家领先公司的科学家和工程师组成的紧密联盟，这些公司关注这项技术的发展，并在两个关键领域展示其适用性和优势。我们还与欧洲领先的mK冷却器中心（赫尔辛基工业大学）密切合作。英国处于非常有利的位置，可以从这项真正令人兴奋的新技术中获益，而该项目将为其实现播下种子。

We intend to develop a new user-friendly technology that would enable small devices to be cooled to exceedingly low temperatures (<100mk). Such a capability will allow diverse and futuristic applications to flourish. These include the detection of black holes, cancer detection and quantum computing. We propose to do this by using an electronic cooling process where relatively energetic (hot) carriers (electrons or holes) quantum mechanically tunnel out of a medium, thereby causing the average electronic temperature in the medium to decrease. The application of this process to realise extremely low temperatures is very new, and we want to greatly improve its efficiency by introducing a new generation semiconductor SiGe into the design of the electronic cooler and, along with it, the well developed silicon processing techniques - so that, ultimately, such coolers can be produced economically and to industrial standards. Coolers will be fabricated around the periphery of a small silicon chip with thermal links to the active device ( payload ) mounted in the centre of the chip. This requires very good thermal design such that the electronic cooler efficiently cools the payload. However, in some cases, it is only necessary to cool the electrons / not the lattice atoms; here SiGe gives a lot of flexibility in controlling the thermal coupling between the electrons and the lattice. Such electronic coolers can operate from a starting temperature of 0.3K, which can be produced by a cryogenic fluid-free closed-cycle helium cryostat, so that a turn-switch technology can be envisaged enabling access to ~10mK working environments. This will be a huge technology step forward, as existing techniques require massive and complex cryogenic fluid-based equipment.During the first phase of the project we will examine several approaches to the realisation of effective electronic cooling, exploiting the wide range of fundamental electronic conditions that can be obtained at very low temperatures in SiGe with its associated metal silicides / thereby enhancing carrier transport and thermoelectric effects. The new coolers will then be tested in two areas of great topical interest, namely radiation detectors and quantum information devices. They could dramatically enhance our ability to detect, for example, the photons that emanate from the earliest black holes, with satellite-based detectors operating at <100mK. And, very significantly, such detectors could revolutionize the fluorescence light detection that is used extensively in biomedical research, enabling advances in our understanding of genetically-based diseases (e.g. cancer) and the workings of a single cell. Furthermore, the computational vista that is opened-up by the quantum computing era requiring qubit devices operating at 10-20mK, is truly awe inspiring. Warwick is co-ordinating the project and has assembled a tightly knit consortium of scientists and engineers with appropriate expertise from four UK universities -Warwick, Cardiff, Leicester and London(Royal Holloway) - and four leading-edge companies, concerned with the development of this technology and the demonstration of its applicability and advantages in two key areas. We are also working closely with Europe's leading centre on mK coolers (Helsinki University of Technology). The UK is exceedingly well positioned to derive benefit from this genuinely new and exciting technology, and this project will sow the seeds for its realisation.