A Diamond Bridge to Phase Slip Physics

计量学--测量的科学--支撑着我们每天遇到的几乎所有事情。计量学的一个日常例子是称出非常小的重量的药物，以提供准确的剂量。在这种情况下，如果对质量单位没有明确和共同的理解，很容易对患者造成可怕的后果。质量单位-千克-在历史上是由一件由白金制成的实物定义的，存放在巴黎郊区的一个保险库里，在世界各地保存着几个复制品。这些副本不可避免地是不完美的，因为每个副本中的铂原子数量永远不可能完全相同，因此千克的定义中不可避免地会出现小错误。然而，自2019年以来，千克已被重新定义为自然的基本常量，并在某种程度上违反直觉地以电子方式测量。因此，这需要在电气测量单位--伏特(电压)、欧姆(电阻)和安培(电流)--上达成一致，这在任何灯泡包装中都是常见的。在这三个电子单位中，我们对伏特和欧姆的大小有非常精确的一致，这两个单位都是由量子力学实验的结果定义的，并且精确度非常高。然而，安培仍然缺乏自己的量子力学定义，而是用其他单位来定义。有许多建议让系统利用量子力学来提供一个独立而准确的安培定义。一种这样的提议使用超导体--一种在极低温度下失去所有电阻的材料，本身就是大规模的量子力学对象。然而，到目前为止，使用超导体来制定量子电流标准一直是困难的，因为人们认为有必要制造非常微小的结构--比典型的人类头发窄数百倍--以诱导出定义安培的必要行为。这里提出的研究将致力于量子力学对安培的定义，使用一种替代材料-超导钻石-来取代更传统的超导材料。在以前的工作中，我们已经发现，金刚石薄膜的内部结构允许我们复制定义安培所必需的先决条件行为，但在相对较大的物理规模--只比人的头发窄几十倍！尽管这看起来仍然很小，但制造和测量这种大小的物体比以前的方法简单得多。我们将用薄的超导金刚石薄膜制造电路，这种薄膜旨在帮助我们从量子力学的角度定义安培的大小。超导钻石独特的内部结构导致了许多其他有希望的量子技术应用，这些应用也将在本研究过程中探索。

Metrology - the science of measurement - underpins almost everything we encounter on a daily basis. An everyday example of metrology is when very small weights of medicine are weighed out to give precise doses. In this instance, without a clear and common understanding of the unit of mass, there could easily be dire consequences for the patient. The unit of mass - the kilogram - was historically defined by a physical object made of platinum and housed in a vault in the outskirts of Paris, with several copies held around the world. These copies were unavoidably imperfect, in that one could never have the exact same number of platinum atoms in each copy, and hence small errors in the definition of the kilogram were inevitable.Since 2019, however, the kilogram has been redefined in terms of the fundamental constants of nature and, somewhat counterintuitively, measured electronically. This therefore requires a common agreement in the units of electrical measurement - the volt (voltage), the Ohm (resistance), and the Ampere (current) - as is familiar from any light bulb packaging. Of these three electrical units, we have a very precise agreement on the magnitude of a volt and an Ohm, both of which are defined by the results of quantum mechanical experiments and are precise to a very high degree. The Ampere, however, still lacks a quantum mechanical definition of its own and is defined in terms of other units.There are numerous proposals for systems that exploit quantum mechanics to provide an independent and precise definition of the Ampere. One such proposal uses superconductors - materials that lose all electrical resistance at very low temperatures and are large scale quantum mechanical objects in of themselves. Using superconductors to make a quantum current standard, however, has so far been difficult because it has been thought necessary to make very small structures - many hundreds of times narrower than a typical human hair - to induce the necessary behaviour to define the Ampere. The research proposed here will work towards a quantum mechanical definition of the Ampere that uses an alternative material - superconducting diamond - in place of more traditional superconducting materials. In previous work, we have found that the internal structure of thin diamond films allows us to reproduce the prerequisite behaviours necessary for the definition of the Ampere, but at a comparatively large physical scale - only tens of times narrower than a human hair! Though this still seems small, making and measuring objects of this size is vastly more simple than previous approaches. We will make electrical circuits out of thin superconducting diamond films that are designed to help us quantum mechanically define the magnitude of the Ampere. The unique internal structure of superconducting diamond results in a host of other promising applications in quantum technologies that will also be explored during the course of this research.