Quantum many-body information

量子多体信息

• 批准号: RGPIN-2014-06630
• 负责人: Poulin, David
• 金额: $ 3.28万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567937
• 关键词: Quantum; many; body; information

Microscopic particles, such as electrons, atoms, and certain microfabricated devices, do not behave as common sense would dictate. Instead, they obey the strange laws of quantum mechanics. These mathematical laws predict for instance that a microscopic particle can be at two places at the same time. While it is hard, if not impossible, to get an intuitive sense about these laws, they are mathematically well understood, they have lead to many scientific predictions, and they have never been contradicted by an experiment. It is by studying the laws of quantum mechanics that devices such as the laser and the transistor were theoretically discovered, before being fabricated. These two devices led to the information revolution, which has impacted all spheres of human activity. While quantum mechanics is at the heart of the information age, the information itself remains classical: the bits processed by a smartphone do not take two different values at a given time, or any such quantum weirdness. Quantum information science is preparing the next information revolution, where quantum mechanical effects are harnessed to enhanced our information processing ability. Quantum communication systems enable unconditionally secure private communication (in contrast to current cryptographic schemes that can be broken with sufficient computing power). Quantum information processors offer an exponential speed-up for certain computations such as factoring integers (with applications in code breaking) and the simulation of quantum mechanical systems (with applications in physics, chemistry, and biology). And these few examples are only the tip of the iceberg. But quantum systems are extremely vulnerable to errors of all kinds, which poses major roadblock to the development of these technologies. If left unattended, these errors will quickly corrupt the quantum information. Scientists have devised fault-tolerant quantum computation, a set of methods to cope with these errors, which is the central theme of my research. While this remedy is well founded theoretically, it entails an explosion of resources required to quantum compute. For instance, with existing schemes, it takes several millions of noisy quantum bits to do the job of a single clean quantum bit. This overhead represents a serious obstacle to the realization of certain quantum technologies, and the main objective of this research proposal is to find theoretical methods to significantly reduce that overhead. Obviously, improving the quality of the physical devices is one way to suppress the overhead. However, it is by improving the software, i.e. the fault-tolerant techniques themselves, that the most significant improvement can be obtained. In the next five years, my NSERC supported research will combine ideas and techniques from theoretical computer science and many-body physics in innovative ways to reduce this overhead. This will be achieve by 1) Enhancing the ways in which fault-tolerant techniques are currently being decoded; 2) Devising new ways to manipulate information fault-tolerantly; and 3) Discovering new phases of matter that naturally protect quantum information. Much like the field itself, my approach is multidisciplinary. I have acquired a unique expertise in these research areas and have assembled an interdisciplinary team of talented young researchers. With this team, I will continue to propose new innovative fault-tolerant methods that will take quantum information processing from a theoretical dream to reality. Canada is already at the forefront of quantum information, and my program will contribute to increase our knowledge in this field and create opportunities for students to learn and apply this knowledge.

微观粒子，如电子、原子和某些微制造装置，其行为并不像常识所指示的那样。相反，它们遵循量子力学的奇怪定律。例如，这些数学定律预测一个微观粒子可以同时出现在两个地方。虽然很难（如果不是不可能的话）对这些定律有一个直观的认识，但它们在数学上是很容易理解的，它们导致了许多科学预测，而且它们从来没有被实验推翻过。正是通过对量子力学定律的研究，诸如激光和晶体管之类的器件才在理论上被发现，然后才被制造出来。这两种设备导致了信息革命，影响了人类活动的各个领域。虽然量子力学是信息时代的核心，但信息本身仍然是经典的：智能手机处理的比特在给定的时间内不会有两个不同的值，也不会有任何类似的量子怪异现象。量子信息科学正在准备下一次信息革命，利用量子力学效应来增强我们的信息处理能力。量子通信系统可以无条件地保证私有通信的安全（与当前的密码方案相比，只要有足够的计算能力，就可以被破解）。量子信息处理器为某些计算提供了指数级的加速，例如分解整数（用于密码破译）和模拟量子力学系统（用于物理、化学和生物学）。这几个例子只是冰山一角。但量子系统极易受到各种错误的影响，这对这些技术的发展构成了主要障碍。如果不加以注意，这些错误将迅速破坏量子信息。科学家们设计了容错量子计算，一套处理这些错误的方法，这是我研究的中心主题。虽然这种补救措施在理论上是有充分根据的，但它需要量子计算所需的资源爆炸式增长。例如，在现有的方案中，需要数百万个嘈杂的量子比特来完成一个干净量子比特的工作。这种开销是实现某些量子技术的严重障碍，本研究计划的主要目标是找到显著降低这种开销的理论方法。显然，提高物理设备的质量是抑制开销的一种方法。然而，只有通过改进软件，即容错技术本身，才能获得最显著的改进。在接下来的五年里，我的NSERC支持的研究将以创新的方式结合理论计算机科学和多体物理学的思想和技术来减少这种开销。这将通过以下方式实现：1)增强目前对容错技术的解码方式；2)设计新的信息容错操作方法；3)发现自然保护量子信息的物质的新阶段。就像这个领域本身一样，我的方法是多学科的。我在这些研究领域获得了独特的专业知识，并组建了一支由才华横溢的年轻研究人员组成的跨学科团队。与这个团队一起，我将继续提出新的创新容错方法，将量子信息处理从理论梦想变为现实。加拿大已经处于量子信息的前沿，我的项目将有助于增加我们在这一领域的知识，并为学生创造学习和应用这些知识的机会。