Spin-photon interfaces based on isoelectronic centers in semiconductors

量子网络使用光子来传输量子态，并在处理节点之间分发纠缠；它们实现了分布式计算和安全通信。它们是由转换静止量子比特和光子量子比特的物理接口构建的。固态自旋量子比特提供了最清晰的可伸缩性途径，被积极地发展为自旋-光子界面。 我的团队已经成功地率先使用等电子中心(IC)作为自旋-光子界面，这是一种光学可寻址的半导体缺陷。在上一个资助周期中，我们为他们的理解做出了重大贡献，并展示了两个其他系统无法比拟的战略优势：NV中心的高光学均匀性和外延量子点的大偶极矩。此外，我们还揭示了轻孔和重孔三子的存在，并展示了新的和强大的光学控制方案。这些成就表明我们有能力在这一领域独立开发新的研究方向。 鉴于ICS提供了极具吸引力的机会，本资助周期致力于进一步推进对这一自旋量子比特系统的研究。更具体地说，我建议阐明自旋弛豫和退相干机制，并利用它们的独特特征来解决阻碍基于半导体的自旋-光子界面发展的两个突出问题： 直接带隙半导体中的自旋相干时间很短。为了解决这个问题，我们利用了1)O和Te IC在II-VI材料中提供的稀薄核自旋环境和2)束缚自旋在几个核上的极端局域化。这两个方面可以产生局部的“无核自旋”环境，在这种环境中，电子或空穴波函数下没有核自旋，从而抑制了这种主要的退相干机制。 用于光学初始化、控制和单次读出的实际方案是相互不兼容的。半导体纳米结构所面临的这一重要问题是通过利用单一磁场配置中的轻空穴和重空穴状态来解决的：轻空穴三重子为初始化和控制提供朗姆达结构，重空穴三重子为读出提供循环跃迁。 通过开发一种原创方法并解决两个根本限制，我们的研究计划致力于在量子信息领域产生最高的科学影响，量子信息是一个有望给信息技术带来革命性变化的重要研究领域。在短期内，该项目使学生能够在经典和量子光学、固态物理和器件以及精密仪器方面培养出色的实验技能。这些技能在信息和通信行业非常受欢迎，信息和通信行业在过去十年里一直是加拿大经济增长最快的部门。

Quantum networks use photons to transport quantum states and distribute entanglement between processing nodes; they enable distributed computation and secure communications. They are built from physical interfaces converting stationary and photon qubits. Providing the clearest paths to scalability, solid-state spin qubits are actively developed as spin-photon interfaces. My group has successfully pioneered the use of isoelectronic centers (ICs), an optically-addressable semiconductor defect, as spin-photon interfaces. In the last grant cycle, we have made significant contributions to their understanding and demonstrated two strategic advantages that no other system combines: the high optical homogeneity of NV centers and the large dipole moments of epitaxial quantum dots. In addition, we have revealed the existence of light-and heavy-hole trions and demonstrated new and powerful optical control schemes. These accomplishments demonstrate our capacity to independently develop new research directions in this field. In the light of the compelling opportunities offered by ICs, this grant cycle is dedicated to further advancing the research on this spin qubit system. More specifically, I propose to elucidate spin relaxation and decoherence mechanisms and exploit their distinctive characteristics to address two outstanding issues impeding the development of semiconductor-based spin-photon interfaces: Spin coherence times in direct gap semiconductors are short. To address this issue, we take advantage of 1) the dilute nuclear spin environment offered by O and Te ICs in II-VI materials and 2) the extreme localization of the bound spin over a few nuclei. These two aspects can yield a local “nuclear-spin-free” environment where no nuclear spin is located underneath the electron or hole wavefunction, thereby suppressing this dominant decoherence mechanism. Actual schemes for optical initialization, control, and single-shot read-out are mutually incompatible. This important issue facing semiconductor nanostructures is solved by exploiting both light- and heavy-hole states in a single magnetic field configuration: light-hole trions provide the lambda structure for initialization and control and heavy-hole trions provide the cycling transition for read-out. By developing an original approach and by addressing two fundamental limitations, our research program strives for the highest scientific impact in quantum information, a prominent research field that promises to revolutionize information technologies. In the short term, this program enables students to develop outstanding experimental skills in classical and quantum optics, solid-state physics and devices, and precision instrumentation. These skills are highly sought in information and communication industry, which has been the fastest growing sector of the Canadian economy over the last ten years.