Non-binary quantum logic with trapped ions

利用量子力学进行新型计算和研究无法以其他方式进行建模的物理现象的前景引发了人们对量子计算机想法的合理兴奋。尽管如此，实际的大规模量子计算机仍然离我们很远，在实现最热门的应用之前，需要对现有硬件进行许多数量级的改进。在这个发现补助金申请中描述的研究计划的长期目标是通过开发在捕获的离子量子比特中存储和操纵信息的技术来增加可实现的量子处理器的信息复杂性：双态量子比特的多态推广。操纵量子点的实用技术的发展，可以在同一物理设备中编码更多的信息，这可能是实现建造大规模量子计算机目标的一条重要捷径。这笔资金将建立一个原子量子信息科学的研究计划，专注于解决量子比特实验实现的初始挑战。将许多量子比特连接到一个算法中而不破坏它们所携带的信息是量子计算的主要挑战。缓解这一挑战的一种可能方法是每个捕获离子（或其他物理量子位）使用更多的状态，以减少执行给定算法所需的离子数量。尽管捕获离子量子比特取得了令人印象深刻的进展，但使用离子作为多级量子比特仍然是一个假设的概念：没有实验证明了基于量子比特进行大规模算法所需的所有操作。 我们建议研究这些构建块操作，例如如何在单个qudits上进行逻辑门或纠缠qudits对，或者如何可靠地读出计算结果。需要这些初步研究来评估该方法的实际前景，但这些研究的结果有望最终为量子处理器的开发提供种子，该处理器使用多状态离子来获得比每个离子仅使用两个状态更高的计算能力。通过这项研究计划开发的实验进展和理论理解将对我们利用量子力学补充传统计算能力的能力产生持久的影响。该提案要求为将进行实验的本科生、研究生和博士后研究人员的工资提供资金，沿着他们参加科学会议的旅费、实验用品和设备以及与发表结果有关的费用。这将使加拿大受益，为培训各种高素质人员提供资金，这些人员将发展为明天的量子技术做出贡献所需的技能和专业知识。

The prospect of harnessing quantum mechanics to perform new types of computation and to investigate physical phenomena that cannot be tractably modeled in other ways has sparked justifiable excitement over the idea of quantum computers. Nevertheless, practical large-scale quantum computers remain far from our reach, with many orders of magnitude of improvement required of existing hardware before the most-hyped applications can be accomplished. The long-term goal of the research program described in this Discovery Grant application is to increase the informational complexity of attainable quantum processors by developing techniques to store and manipulate information in trapped ion qudits: the multi-state generalization of two-state qubits. The development of practical techniques to manipulate qudits, which encode more information in the same physical device, may present an important shortcut toward the goal of building a large-scale quantum computer. This funding will establish a research program in atomic quantum information science, focusing on tackling initial challenges in the experimental implementation of qudits.Linking many qubits into an algorithm without destroying the information they carry is the primary challenge in quantum computation. One possible way to mitigate this challenge is to use more states per trapped ion (or other physical qubit) to reduce the number of ions required to perform a given algorithm. Despite impressive progress with trapped ion qubits, the use of ions as multi-level qudits remains a mostly hypothetical concept: no experiments have demonstrated all the operations needed to carry out large-scale algorithms based on qudits. We propose to investigate these building-block operations, such as how to carry out logic gates on single qudits or entangle pairs of qudits, or how to reliably read out the result of a computation. These initial studies are needed to assess the practical promise of the approach, but the results of these investigations are hoped to eventually seed the development of a quantum processor which uses multi-state ions to attain more computational power than if it had used only two states per ion. The experimental advances and theoretical understanding developed through this research program will have lasting impact on our ability to harness quantum mechanics to complement conventional computing capabilities. This proposal requests funding for the salaries of the undergraduate, graduate, and postdoctoral researchers who will carry out the experiments, along with funding for their travel to scientific conferences, supplies and equipment for their experiments, and costs associated with publishing results. This will benefit Canada by funding the training of various highly-qualified personnel who will develop the skills and expertise necessary to contribute to tomorrow's quantum technologies.