Scalable semiconductor quantum technologies

经典晶体管促成了计算机领域的第一次技术革命。然而，信息处理的最终限制是由量子力学而不是经典物理学决定的。近几十年来，量子信息科学出现了一个新的范式，预示着第二次技术革命——“量子时代”。例如，有效地模拟服从量子力学的复杂物理系统的能力，将使医学、能源、化学、材料工程和许多其他领域取得无数的新进展。解开这些进步的关键是将理论量子电路转化为现实世界的设备，特别是允许任意尺寸缩放的架构。然而，由于退相干的过程，量子信息是极其脆弱的。通过应用量子纠错的理论工具或利用拓扑保护模式来存储量子态，证明退相干可以在实际设备中克服仍然是一个挑战。******提出的研究计划使用两个有前途的实验平台来测试这两种策略。第一种策略是利用自旋量子比特（由电子自旋的量子态定义的物体）来探索量子纠错。单个电子被限制在一个被称为量子点的空间小区域中，它的自旋可以用电磁场来操纵。我们选择硅作为宿主材料，因为自旋量子比特在硅中具有很长的相干时间，并且量子点可以使用cmos兼容的制造方法形成，具有很大的可扩展性潜力。我们提出了一种新的网络架构，用于实现具有非常高容错性的量子纠错方案，称为表面码。第二种策略，拓扑保护量子比特，在超导体-半导体混合器件中进行了探索，旨在实现称为马约拉纳费米子或准费米子的特殊状态。我们将利用一个独特的、可扩展的材料系统，基于InSb量子阱，来设计拓扑量子比特的操作和读出的首次演示。******第三个重点是碳纳米管（CNT）纳米机械谐振器，并探索它们在原子尺度上测量力的潜力。这建立在我们已经证明的在微秒时间尺度上测量碳纳米管振动幅度的亚纳米变化的能力之上。我们将应用这一方法来检测接枝到碳纳米管上的单个磁性分子的自旋状态，这可以作为一种新的扫描探针技术的基础。

The classical transistor enabled the first technological revolution in computing. The ultimate limits on information processing, however, are determined by quantum mechanics rather than classical physics. A new paradigm of quantum information science has emerged in recent decades that promises a second technological revolution - the ‘quantum age'. The ability to efficiently simulate complex physical systems that obey quantum mechanics, for example, will enable untold new advances in medicine, energy, chemistry, materials engineering and many other fields. The key to unlock these advances is translating theoretical quantum circuits into real world devices, particularly with architectures that allow scaling to arbitrary size. Quantum information, however, is extremely fragile due to the process of decoherence. It remains a challenge to show that decoherence can be overcome in real devices, either by applying the theoretical tools of quantum error correction, or by exploiting topologically protected modes to store quantum states. ******The proposed research program uses two promising experimental platforms to test both strategies. The first strategy, using quantum error correction, is explored using spin qubits – objects defined by the quantum states of an electron's spin. A single electron is confined in a small region of space called a quantum dot, and its spin can be manipulated with electromagnetic fields. We choose silicon as the host material because spin qubits can have very long coherence times in silicon, and quantum dots can be formed using CMOS-compatible fabrication methods, lending a great potential for scalability. We propose a novel network architecture for implementing a quantum error correction scheme with a very high tolerance for errors, called a surface code. The second strategy, topologically protected qubits, is explored in superconductor-semiconductor hybrid devices designed to realize special states known as Majorana fermions or parafermions. We will exploit a unique and scalable material system, based on InSb quantum wells, to engineer first demonstrations of manipulation and readout of topological qubits. ******A third thrust is on carbon nanotube (CNT) nano-mechanical resonators and explores their potential for measuring forces at the atomic scale. This builds on our demonstrated ability to measure sub-nanometer changes in the CNT vibration amplitude on microsecond timescales. We will apply this to detect the spin states of individual magnetic molecules grafted onto the CNT, which could serve as a basis for a new scanning probe technology.