Dopant-Based Scalable Platform in Silicon for Quantum Information Processing

在数字革命之后，现在每个人都在大量使用微电子行业提供的硅晶体管：它们不仅是超级计算机的基本元素，而且是已经渗透到我们现代生活的方方面面的所有电子设备(手机、PC、GPS、汽车、电视、互联网路由器)。我们现代社会的这场革命带来了更多的舒适，并使科学得以进步。 计算机芯片的改进一直是通过缩小晶体管的尺寸来推动的，但这种缩放现在已经达到了一个极限，对单掺杂原子准确位置的敏感性和量子效应都是进一步缩小规模的主要障碍，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。一些学术界和工业界的主要参与者(如英特尔)在低温下探索用于量子计算的超大规模晶体管：晶体管通道随后表现为一个量子点，限制单个电子，其自旋(而不是电荷)用于编码量子信息。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，而且设备仍然容易出现掺杂变化，阻碍了可扩展架构的出现。 在这项发现拨款(DG)中，我们转而考虑自然存在于晶体管中的掺杂剂的核自旋，以编码量子信息。他们已经证明了记录相干时间，比量子点中电子自旋的记录相干时间大几个数量级。 我们将首先解决操作核自旋量子比特的关键挑战：可寻址。这种DG将把超标度晶体管对单个掺杂剂的强烈敏感度转化为优势。超比例晶体管的小尺寸在这里将是一个关键的优势，因为它提供了一种将电场和磁场聚焦到良好隔离的核自旋上的方法。 我们将重点研究具有高核自旋的掺杂剂，这些掺杂剂提供必要的冗余来编码纠错后的逻辑量子比特，并允许对自旋进行电子操作，这是可伸缩性的关键资产。 然后，我们将利用无损超导谐振器，通过电子自旋来调节两个核自旋之间的相互作用，从而开发出位于遥远晶体管中的两个核自旋之间的耦合方案。 这一DG将为经典电子行业提供一条前进的道路，将其用于未来的量子计算机。我们的研究将提供量子处理器的基础：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。我们预计我们的设备将显示前所未有的功能，如内置纠错、长一致性和可扩展性。这个DG有可能为加拿大提供微电子行业的颠覆性设备，以及量子计算竞赛中的尖端技术。

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.