CAREER: Fast coherent and incoherent control of atomic ions in scalable platforms

职业：在可扩展平台中对原子离子进行快速相干和非相干控制

• 批准号: 2338897
• 负责人: Karan Mehta
• 金额: $ 55万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-01 至 2029-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2338897&HistoricalAwards=false
• 关键词: CAREER; Fast; coherent; incoherent; control

Individual ions immobilized in vacuum and precisely controlled with lasers constitute a leading platform for quantum computing (QC), simulation, and metrology. Current academic and industrial QC systems operating on up to a few tens of qubits are however far from the millions required for fault-tolerant universal QC, as may be required for practically useful quantum advantage. This scaling represents a challenge that will be met only with innovations in the basic physical techniques used for qubit control, and simultaneously the classical hardware interfacing with qubits. The proposed research will invent and experimentally explore physical methods for ion qubit control capable of overcoming fundamental limitations in speed and error of current approaches. Ion qubit control is generally performed with laser fields, typically assumed to be in spatial profiles essentially uniform over the atom's extent due to conventional implementations with free-space laser beams. This imposes serious limitations on a range of basic functionalities, compromising operation speeds, errors achievable, and physical architectures. Chip-integrated hardware platforms that the PI has pioneered facilitate scaling, and furthermore enable practical and stable delivery of tailored spatial field profiles, where fine spatial variations of the field profile can play a critical role in dynamics. The present work will explore new atom-light interactions enabled in these configurations, thereby opening a new frontier for quantum control in scalable atomic systems. The research immerses PhD and undergraduate researchers in ideas drawing deeply from both classical optics/photonics and quantum science, an intersection of broad and growing importance both in research and for industry workforce. Outreach involving active participation by local middle and high school students is planned. The proposed work explores how structured light fields can address the fundamental challenges in scaling trapped-ion quantum systems -- how can we reduce limiting operation times for both incoherent (laser cooling, readout) and coherent (quantum logic) operations, while further reducing limiting infidelities? Since this work leverages scalable hardware platforms and foundry-fabricated devices to address these questions, achieved advances will directly impact practical large-scale systems in development. Furthermore, the techniques pursued here will inform efforts in precision metrology and searches for new physics based on atomic spectroscopy, in which the PI is also actively involved in collaborations internationally. Key to the concepts proposed are the ability to tailor spatially structured light fields at the atom location with electric field gradients or curvatures along desired directions, but at nulls in the electric field and thus intensify itself. This allows for driving sideband transitions that couple to ion motion with suppressed off-resonant carrier excitation, or driving of particular desired electric quadrupole or octupole transitions with minimal off-resonant couplings. Integrated photonic delivery offers a route to design such delivered beams with high precision, and furthermore deliver the spatially varying profiles to atomic ions with the few nm-level stability required for realization of these concepts. Specific aims within this program include realization of Doppler laser cooling of ion motion 50x faster than current methods allow, fast and broadband cooling to the quantum ground state in novel proposed schemes utilizing tailored optical field profiles, probing of optical quadrupole transitions in higher-order Hermite-Gauss modes, and pursuit of integrated realization of multi-qubit logic with 10^-4 level error, all within a scalable optical platform.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

单个离子固定在真空中，用激光精确控制，构成了量子计算（QC）、模拟和计量的领先平台。然而，目前的学术和工业QC系统运行在几十个量子位上，与容错通用QC所需的数百万个量子位相差甚远，这可能需要实际有用的量子优势。这种扩展代表了一个挑战，只有在用于量子比特控制的基本物理技术上进行创新，同时与量子比特进行经典硬件接口，才能解决这个挑战。提出的研究将发明和实验探索离子量子比特控制的物理方法，能够克服当前方法在速度和误差方面的基本限制。离子量子位控制通常是用激光场进行的，由于传统的自由空间激光束实现，通常假设在原子范围内的空间轮廓基本上是均匀的。这对一系列基本功能造成了严重的限制，影响了操作速度、可实现的错误和物理体系结构。PI率先推出的芯片集成硬件平台促进了扩展，并且能够实现定制空间场剖面的实用和稳定交付，其中场剖面的精细空间变化可以在动力学中发挥关键作用。目前的工作将探索在这些配置中启用的新的原子-光相互作用，从而为可扩展原子系统中的量子控制开辟新的前沿。这项研究让博士和本科生的研究人员沉浸在经典光学/光子学和量子科学的思想中，这是一个在研究和行业劳动力中广泛且日益重要的交叉点。计划让当地中学生和高中生积极参与外展活动。提出的工作探讨了结构光场如何解决缩放困离子量子系统的基本挑战-我们如何减少非相干（激光冷却，读出）和相干（量子逻辑）操作的限制操作时间，同时进一步减少限制不可靠性？由于这项工作利用可扩展的硬件平台和铸造厂制造的设备来解决这些问题，因此取得的进展将直接影响开发中的实际大规模系统。此外，这里所追求的技术将为精确计量和寻找基于原子光谱学的新物理学的努力提供信息，PI也积极参与国际合作。提出的概念的关键是能够在原子位置定制空间结构光场，使其具有沿期望方向的电场梯度或曲率，但在电场的零点处，从而加强自身。这允许驱动边带跃迁与抑制非谐振载流子激励耦合到离子运动，或驱动特定所需的电四极或八极跃迁与最小的非谐振耦合。集成光子传输为设计这种高精度传输光束提供了一条途径，并且进一步以实现这些概念所需的几纳米级稳定性向原子离子提供空间变化的轮廓。该项目的具体目标包括实现比当前方法快50倍的离子运动的多普勒激光冷却，利用定制的光场轮廓在新提出的方案中快速和宽带冷却到量子基态，探测高阶埃米-高斯模式下的光学四极跃迁，以及追求具有10^-4级误差的多量子位逻辑的集成实现，所有这些都在可扩展的光学平台内。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。