Dopant-Based Scalable Platform in Silicon for Quantum Information Processing

随着数字革命的到来，现在每个人都在大量使用微电子工业提供的硅晶体管：它们不仅是超级计算机的基本元素，而且是侵入我们现代生活方方面面的所有电子设备（手机、个人电脑、GPS、汽车、电视、互联网路由器等）的基本元素。现代社会的这场革命给我们带来了更多的舒适，并使科学取得了进步。计算机芯片的改进是通过减小晶体管的尺寸来推动的，但是这种缩放现在已经达到了极限，对单个掺杂原子精确位置的敏感性和量子效应都是进一步缩小尺寸的主要障碍，这要求探索高度创新和颠覆性的方法来进一步发展硅计算。一些学术和主要工业参与者（如英特尔）正在探索低温下用于量子计算的超大尺寸晶体管：晶体管通道的行为就像一个量子点，限制单个电子的自旋（而不是电荷）被用来编码量子信息。然而，电子自旋相干时间是有限的，在系统退相干之前只允许非常有限的操作，并且器件仍然容易发生掺杂变化，阻碍了可扩展架构的出现。在这个发现基金（DG）中，我们转而考虑天然存在于晶体管中的掺杂剂的核自旋来编码量子信息。他们已经证明了创纪录的相干时间，比量子点中电子自旋的相干时间大几个数量级。我们将首先解决操作核自旋量子位的关键挑战：可寻址性。这种DG将把超尺度晶体管对单个掺杂物的强灵敏度变成一种优势。超大尺寸晶体管的小尺寸将是一个关键的优势，它提供了一种将电场和磁场聚焦到隔离良好的核自旋上的方法。我们将重点研究具有高核自旋的掺杂剂，它提供必要的冗余来编码纠错的逻辑量子位，并允许对自旋进行电气操作，这是可扩展性的重要资产。然后，我们将利用无损超导谐振器开发位于远处晶体管的两个核自旋之间的耦合方案，通过电子自旋介导两个核自旋之间的相互作用。这种DG将通过将其用于未来的量子计算机，为经典电子工业提供一条前进的道路。我们的研究将提供量子处理器的构建模块：由位于晶体管通道中的掺杂剂的核自旋形成的优秀量子比特。我们希望我们的设备能够展现出前所未有的能力，比如内置纠错、长相干性和可扩展性。这个DG有潜力为加拿大提供颠覆性的微电子工业设备，并在量子计算竞赛中处于领先地位。

Following the digital revolution, everyone is now massively using silicon transistors provided by microelectronics industry: They are the basic element not only of supercomputers, but of all electronic devices that have invaded every aspect of our modern lives (cell phones, PCs, GPS, cars, TV, internet router, .). This revolution of our modern society has brought increased comfort and allowed progress in science. Improvement of computer chips has been driven by reducing the size of the transistors, but this scaling has now reached a limit where both sensitivity to the exact position of single dopant atoms and quantum effects present major obstacles to further downscaling, calling for the exploration of highly innovative and disruptive approaches to further the development of computing in silicon. Several academic and major industrial players (as Intel) explore ultrascaled transistors at low temperature for quantum computation: The transistor channel then behaves as a quantum dot confining a single electron whose spin (instead of charge) is used to encode quantum information. Yet, the electron spin-coherence time is limited, allowing only for a very limited number of operations before the system decoheres, and the devices are still prone to dopant variability, preventing scalable architecture to emerge. In this discovery grant (DG) we instead consider nuclear spins of dopants, naturally present in transistors, to encode the quantum information. They have already demonstrated record coherence times, several orders of magnitude larger than the ones of electron spins in quantum dots. We will first address the key challenge for operating nuclear spin qubits: addressability. This DG will turn the strong sensitivity of ultrascaled transistor to individual dopants into an advantage. The small size of ultrascaled transistors will here be a key advantage by providing a means to focus electric and magnetic fields onto the well isolated nuclear spin. We will focus our research on dopants with high nuclear spin which provide the necessary redundancy to encode error-corrected logical qubits and allow for electrical manipulation of the spin, an essential asset to scalability. We will then develop coupling schemes between two nuclear spins located in distant transistors by using a lossless superconducting resonators, mediating the interaction between two nuclear spins via an electron spin. This DG will provide a way forward for the classical electronics industry by bringing it to use for future quantum computers. Our research will provide the building blocks of a quantum processor: Excellent quantum bits formed by the nuclear spin of a dopant located in the transistor channel. We expect our device to show unprecedented capabilities, such as built-in error correction, long coherence and scalability. This DG has the potential to provide Canada with disruptive devices for the microelectronic industry as well as a cutting edge in the race of quantum computation.