Exploring nanowire structures for quantum information - a route to discoveries and new technological applications

探索量子信息的纳米线结构——发现和新技术应用的途径

• 批准号: RGPIN-2018-05109
• 负责人: Ruda, Harry
• 金额: $ 5.97万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=758267
• 关键词: Exploring; nanowire; structures; quantum; information

Classical computers (CC) use classical physics to encode information in binary bits while quantum computers rely on the laws of quantum mechanics (QM) to process information in qubits qubits may simultaneously be in two states due to superposition, and many such qubits can form strongly correlated systems through entanglement, behaving as a single system. Such QM systems are inherently more powerful than CCs, and with sufficiently large numbers of qubits, can solve problems that are intractable with CCs. The search for a perfect platform that simultaneously satisfies requirements of fast quantum control, long coherence times and scalability to thousands of qubits remains a topic of considerable interest. Recently, a new platform based on semiconductor (S) nanowire (NW) heterostructures (HS) has emerged, with qubits showing the fastest electrical spin manipulation times for single spins in QDs. Moreover, the first signatures of Majorana fermions (MFs), which are their own antiparticles and represent the building blocks for topological qubits, have been very recently reported in such NWs. However, these systems are still in their infancy and typically only function in dilution fridge temperatures. NW HS bring: (a) a virtually unlimited choice of materials for both radial and longitudinal HSs as strain may be relieved by unconfined deformation as they grow, and (b) multiple local metal or superconductor (SC) gates may be defined, together with a global back-gate, to provide scalable qubit systems. This proposal examines NW-based schemes addressing shortcomings of current schemes for a scalable QC platform. MF based qubits, through topological protection, should be virtually immune to environment-based decoherence. However, to host them, ballistic (B) NW HS are key - an area where we have demonstrated control over surface state occupation and backscattering to yield state of the art B-NWs; with sufficient quality B-NWs, long thin NWs can be used to enhance immunity. We propose to harness our recent first reports on proximitized SC with high temperature SCs (HTSC), to potentially bring the technology to near-LN2 temperatures something quite new. Next we will explore scalable systems which can be extended into multi-qubit systems. We will also explore the novel possibility of using HTSC/NW-HS systems for gate controlled radiative emission (and two-photon absorption) of entangled photon pairs at elevated temperatures such devices could provide the means to implement “flying” qubits for scalable quantum processing application. We will also explore an alternative platform for dense qubit registers based on self-assembled electron lattices known as the incipient Wigner lattice. This state with entangled e' (spin antiparallel) pairing, can be explored for its' potential for information transmission, computation and memory.

经典计算机（CC）利用经典物理学以二进制比特的形式编码信息，而量子计算机则依靠量子力学（QM）的定律来处理量子比特中的信息。由于叠加，量子比特可能同时处于两种状态，并且许多这样的量子比特可以通过纠缠形成强相关系统，表现为单个系统。这种 QM 系统本质上比 CC 更强大，并且具有足够多的量子位，可以解决 CC 难以解决的问题。寻找一个同时满足快速量子控制、长相干时间和可扩展至数千个量子位的要求的完美平台仍然是人们相当感兴趣的话题。最近，出现了一种基于半导体（S）纳米线（NW）异质结构（HS）的新平台，其量子位显示了量子点中单自旋最快的电自旋操纵时间。此外，最近在此类 NW 中报道了马约拉纳费米子 (MF) 的第一个特征，MF 是它们自己的反粒子，代表拓扑量子位的构建块。然而，这些系统仍处于起步阶段，通常仅在稀释冰箱温度下起作用。 NW HS 带来了：(a) 径向和纵向 HS 的材料选择几乎不受限制，因为在它们生长时，应变可以通过无限制变形来缓解，(b) 可以定义多个局部金属或超导体 (SC) 门以及全局背门，以提供可扩展的量子位系统。该提案研究了基于 NW 的方案，解决了可扩展 QC 平台当前方案的缺点。基于 MF 的量子位通过拓扑保护，实际上应该不受环境退相干的影响。然而，为了容纳它们，弹道 (B) NW HS 是关键 - 在这个领域，我们已经证明了对表面态占据和后向散射的控制，以产生最先进的 B-NW；有了足够的优质B-NW，可以使用细长的NW来增强免疫力。我们建议利用我们最近关于高温 SC (HTSC) 的邻近 SC 的第一份报告，有可能将该技术带到接近 LN2 的温度，这是一种全新的技术。接下来我们将探索可以扩展到多量子位系统的可扩展系统。我们还将探索使用 HTSC/NW-HS 系统在高温下对纠缠光子对进行门控辐射发射（和双光子吸收）的新可能性，此类设备可以为实现可扩展量子处理应用的“飞行”量子位提供手段。我们还将探索基于自组装电子晶格（称为初期维格纳晶格）的密集量子位寄存器的替代平台。这种具有纠缠 e'（自旋反平行）配对的状态可以探索其信息传输、计算和记忆的潜力。