Quantum Mechanics at the Complexity Frontier

复杂性前沿的量子力学

• 批准号: 1520535
• 负责人: Christopher Laumann
• 金额: $ 28.5万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1520535&HistoricalAwards=false
• 关键词: Quantum; Mechanics; Complexity; Frontier

The development of quantum information technology promises to revolutionize both fundamental and applied science. For example, on the fundamental side, we expect that quantum devices will efficiently simulate poorly understood quantum mechanical theories, providing insight into their behavior. On the applied side, such simulations would allow for the design of new nanomaterials and biochemical molecules. The first experimental step in developing quantum devices has been to bring single quanta under complete control. This has mostly been accomplished over the last two decades. Laboratories around the world now routinely trap, isolate and probe individual atoms, ions, electrons, spins and photons. These systems form 'qubits', the elementary building blocks of quantum computers. The next step is to put these qubits together to form quantum circuits, simulators, networks and eventually computers. However, as the number of qubits in a device grows, so too does the complexity of describing and controlling the properties of that device. This complexity underlies the potential power of quantum technology but also brings many theoretical and experimental challenges. This project seeks to address two of these challenges. First, what physical mechanisms can stabilize the multi-qubit systems so as to make them usable quantum devices? One possibility is provided by a recently discovered phenomenon called 'many-body localization'. Usually, the unavoidable presence of disorder in experiments leads to difficulties controlling the qubits. Counter-intuitively, it seems that putting in more disorder can actually help by 'localizing' the quantum information, preventing it from escaping into the environment as noise. Many of the fundamental features of localization remain unknown. By a combination of classical computational and analytical studies, the group aims to elucidate the conditions under which the many-body localized phase arises, the near-term experimental consequences and its potential as an intrinsic platform for quantum computing. Second, what kinds of problems can we expect a quantum computer to be able to solve? There are efficient quantum algorithms for particular problems, such as simulating molecular structure and breaking cryptographic codes. However, the most general optimization problems are believed to be hard even for a quantum computer. What distinguishes these hard problems from the tractable ones is an outstanding open question whose answer has profound consequences. The aim is to develop a better understanding of typical quantum optimization problems through a case study of a canonical example: quantum satisfiability. It is expected that insights into this problem will lead to new heuristic quantum algorithms. A similar line of inquiry in classical computation led to important classical optimization algorithms, such as simulated annealing and belief propagation.From a somewhat more technical point of view, these two projects are related by their reliance on the techniques of disordered statistical mechanics and spin glass theory. Their study will rely on both numerical simulations using large scale classical computer clusters and analytic study using the cavity method and its quantum generalizations. This latter method was developed previously for the study of quantum spin glasses. The projects will help train one to two graduate students in the relevant physics and techniques.

量子信息技术的发展有望改变基本科学和应用科学。例如，在基本方面，我们期望量子设备有效地模拟知识较低的量子机械理论，从而洞悉其行为。在应用的一侧，这种模拟将允许设计新的纳米材料和生化分子。开发量子设备的第一个实验步骤是将单个量子带到完全控制下。在过去的二十年中，这主要是实现的。现在，世界各地的实验室常规捕获，分离和探测单个原子，离子，电子，旋转和光子。这些系统形成“ Qubits”，这是量子计算机的基本构建块。下一步是将这些量楼放在一起以形成量子电路，模拟器，网络和最终的计算机。但是，随着设备中的Qubit数量的增加，描述和控制该设备属性的复杂性也是如此。这种复杂性是量子技术的潜在力量的基础，但也带来了许多理论和实验挑战。该项目旨在应对其中两个挑战。首先，哪些物理机制可以稳定多量系统以使其可用的量子设备？最近发现的一种称为“多体定位”的现象提供了一种可能性。通常，实验中不可避免的障碍存在会导致控制量子位的困难。违反直觉，看来增加更多的疾病可以通过“定位”量子信息来帮助，以防止其逃脱为噪音。本地化的许多基本特征仍然未知。通过经典计算研究和分析研究的结合，该小组旨在阐明多体局部相，近期实验后果及其作为量子计算的内在平台的潜力。其次，我们期望量子计算机能够解决哪些问题？对于特定问题，有有效的量子算法，例如模拟分子结构和破坏加密代码。但是，即使对于量子计算机，最通用的优化问题也很难。这些硬性问题与可访问的问题的区别是一个杰出的公开问题，其答案具有深远的后果。目的是通过对规范示例的案例研究更好地理解典型的量子优化问题：量子可满足性。预计对这个问题的见解将导致新的启发式量子算法。 经典计算中类似的询问线导致了重要的经典优化算法，例如模拟退火和信念传播。从更具技术性的观点来看，这两个项目与它们对无序统计学机制和旋转玻璃理论的技术相关。他们的研究将使用大规模的经典计算机簇和使用腔体方法及其量子概括的分析研究来依靠两个数值模拟。后一种方法先前是用于研究量子自旋玻璃的。这些项目将帮助培训一到两个研究生的物理和技术。