Experimental study of hole spin qubits in gated semiconductor devices for quantum processing and communication applications

众所周知，量子计算机在某些计算和优化任务方面将更加强大，而作为“飞行量子比特”的单光子将提供100%的安全性，防止可能的窃听攻击。固体自旋量子比特在开发量子信息和安全通信应用方面引起了世界范围内迅速增长的兴趣。孤立的电子自旋是量子比特或量子位最自然的两级系统，量子比特是量子计算机的基本元素。至少从可扩展性的角度来看，基于半导体的自旋量子比特形成了构建多量子比特量子处理器的最有前途的平台，因为半导体可以自然地采用先进微电子硅技术的所有发展。迄今为止，绝大多数研究都是在不同半导体材料中的电子自旋量子比特上进行的。与更多研究的电子量子位相比，本提案致力于探索门控量子点器件中孤立的空穴自旋量子位。利用空穴自旋量子比特代表了新兴量子信息和通信技术的新范式。在一个完全填充的半导体价带（即空穴）中缺少电子，可以被视为一个可以移动并具有自旋的正准粒子。对于自旋量子比特的应用，空穴具有许多吸引人的特性。具体来说，空穴具有更强的自旋-轨道耦合，这可以用于更快的自旋操作，并且减少了与周围核自旋的超精细相互作用，以提高量子相干性。此外，价带固有地没有谷，这对于避免不必要的量子位态简并是重要的。我的提案的长期目标是探索空穴自旋量子比特作为量子计算和安全通信的新系统平台。在接下来的五年里，我的研究将集中在门控量子点器件中的单自旋和双自旋空穴量子比特的开发上。利用单孔电偶极子自旋共振（EDSR）、拉比振荡和拉姆齐条纹等不同的实验方法研究空穴自旋量子比特的相干性。我们小组开创的一种先进的锁存协议将用于需要可靠的单次读取自旋量子比特状态的研究。本研究项目获得的基础知识将发表在开放获取的期刊上，可供其他研究和/或对量子技术感兴趣的高科技公司使用。包括加拿大在内的世界各国对量子技术的兴趣日益浓厚。因此，对熟悉量子物理和技术的高素质人才（HQP）的需求不断增长。在本研究过程中培训的HQP将获得加拿大新兴高科技就业市场所需的必要知识和实践技能。

It is well established that quantum computers will be significantly more powerful for certain computation and optimization tasks and that single photons used as "flying qubits" will provide 100% security against possible eavesdropping attacks. Solid-state spin qubits attract a rapidly growing worldwide interest for developing quantum information and secure communication applications. An isolated electron spin is the most natural two-level system for a quantum bit or a qubit, the basic element of a quantum computer. Semiconductor based spin qubits form the most promising platform from at least the scalability point of view for building many-qubit quantum processors, because semiconductors can naturally adopt all developments of the advanced microelectronics silicon technology. The vast majority of studies to date have been performed on electron spin qubits in different semiconductor materials. In contrast to more studied electron qubits, this proposal is devoted to exploration of hole spin qubits isolated in gated quantum dot devices. Using hole spin qubits represent a new paradigm for emerging quantum information and communication technologies. The absence of an electron in a fully filled semiconductor valence band, i.e. a hole, can be treated as a positive quasiparticle which can move and possess spin. Holes possess a number of attractive properties for spin qubit applications. Specifically, holes have much stronger spin-orbit coupling, which can be used for much faster spin manipulations, and a reduced hyperfine interaction with surrounding nuclear spins for improved quantum coherence. Additionally, the valence band is inherently free from valleys, which is important to avoid unwanted degeneracies of qubit states. The long term goal of my proposal is the exploration of hole spin qubits as a new system platform for quantum computing and secure communications. In the next five years, my research will focus on developing single- and two-spin hole qubits in gated quantum dot devices. Coherence properties of the hole spin qubits will be studied by different experimental methods such as single-hole electric dipole spin resonance (EDSR), Rabi oscillations and Ramsey fringes. An advanced latching protocol pioneered in our group will be used in studies requiring reliable single-shot read-out of spin qubit states. The fundamental knowledge attained in this research program will be published in open-access journals and can be used by other researches and/or by high-tech companies interested in quantum technologies. There is growing interest in quantum technologies worldwide, including in Canada. Consequently, there is a growing demand for highly qualified personnel (HQP) familiar with quantum physics and technologies. The HQP trained in the course of this research will acquire necessary knowledge and practical skills required in the emerging high-tech job market in Canada.