Information-processing limitations of quantum systems

量子计算机如果实现，将提供前所未有的计算能力，几乎肯定会对我们的社会产生深远的影响。开发这种巨大的信息处理潜力的愿景是量子信息这一令人兴奋的研究领域的推动力。这一领域所涉及的挑战虽然意义重大，但也为物理学和计算机科学的基本问题提供了新的视角。除了可能给我们提供量子计算机之外，提高我们控制量子系统的技术能力(以及我们对基本物理的基本理解)可能会在其他目前意想不到的方面造福社会。为了实现这些目标，该计划将评估现有的量子信息，并提出存储、操作和传输量子信息的新方法，确定在给定量子系统中物理上可能达到的极限。第一个分项目将开发数值和统计方法，旨在以有效的方式描述复杂的量子系统和过程。随着实验者迅速扩展他们正在研究的量子衬底的曲目，这一点变得越来越重要。第二个子项目将涉及开放量子系统中信息的可靠存储，特别是那些提供某种内在保护的系统。这将有助于纠错和容错计算的理论。此外，这个子项目将通过研究光缆的信息承载能力来促进我们对使用量子态进行通信的理解。最后，第三个分项目将从不同的角度审查现有的技术和物理信息处理限制：这种限制往往为加密原语的安全提供基础。通过努力根据相应的替代安全假设设计协议，该分项目将有助于在未来维持一个可靠的信息安全基础设施。

Quantum computers, if realized, would offer unprecedented computational capabilities and almost certainly have a profound effect on our society. The vision of exploiting this vast information-processing potential is a driving force in the exciting research field of quantum information. The challenges involved in this area, while significant, offer new perspectives on basic questions in physics and computer science. Beyond possibly giving us quantum computers, advancing our technological prowess in controlling quantum systems (as well as our fundamental understanding of the underlying physics) is likely to benefit society in other, currently unanticipated ways. To contribute towards these goals, this program will evaluate existing and propose new ways of storing, manipulating and transmitting quantum information, identifying the limits of what is physically possible in a given quantum system. A first subproject will develop numerical and statistical methods aimed at characterizing complex quantum systems and processes in an efficient manner. This is becoming increasingly relevant as experimentalists are rapidly extending their repertoire of quantum substrates under study. A second subproject will be concerned with the reliable storage of information in open quantum systems, especially those providing a certain type of intrinsic protection. This will contribute to the theory of error-correction and fault-tolerant computing. In addition, this subproject will advance our understanding of communication using quantum states by studying the information-carrying capacity of fiber-optic cables. Finally, a third subproject will examine existing technological and physical information-processing limitations from a different perspective: such restrictions often provide a basis for security of cryptographic primitives. By working towards the design of protocols based on corresponding alternative security assumptions, the subproject will contribute towards maintaining a reliable information security infrastructure into the future.