AF: Large: Collaborative Research: Reliable Quantum Communication and Computation in the Presence of Noise

量子信息科学对信息和通信的本质产生了深刻的理论见解，同时提高了计算机和通信网络能力显着增强的希望。 但这些实际目标的实现受到量子信息固有的脆弱性的阻碍。通过简单冗余获得可靠性的传统方法行不通；相反，容错必须而且原则上可以通过更微妙的技术来获得，这些技术可以在不了解任何有关编码数据的情况下测量和纠正错误。不幸的是，现有的容错量子计算方法需要大量的开销，并且目前对量子通道容量的理解仍然非常有限。 例如，尚不存在可以在不离开代码空间的情况下执行任意容错量子计算的量子代码。 直到最近才发现经典信息的发送速率可以超过长期以来推测的 Holevo 界限。该项目将尝试开发新方法，在存在噪声的情况下实现可靠​​的量子通信和计算。 首先，该研究将通过扩展和描述可纠正错误的类型，以及确定在何种情况下可以或不可能进行这种纠错，来推动量子纠错技术的能力和边界。 第二个目标是发展量子代码、纠缠和多体物理、复杂性理论、密码学和高维几何之间的深层但迄今为止尚未探索的联系。 目的是增进我们对量子代码以及数学、物理和计算机科学相关领域的理解。 最后，该团队将寻求阐明量子通信与其最接近的经典模拟——私人通信之间的细微差别。这项研究致力于为大规模量子计算机的现实实施做出明确的贡献，这将极大地提高人类处理和通信信息的能力。 该研究项目本身是深度跨学科的，汇集了来自工业界和学术界的物理学家、计算机科学家和数学家，并培训学生和博士后。

Quantum information science has yielded deep theoretical insights into the nature of information and communication, while raising the hope of dramatically more capable computers and communication networks. But the achievement of these practical goals is hindered by the inherent fragility of quantum information. Traditional approaches for obtaining reliability through simple redundancy do not work; instead, fault tolerance must, and can, in principle, be obtained through subtler techniques that contrive to measure and correct errors without learning anything about the encoded data.Unfortunately present methods for fault-tolerant quantum computation require significant overhead, and present understanding of quantum channel capacities remain very limited. For example, no quantum code is known on which arbitrary fault-tolerant quantum computation can be performed without leaving the code space. And only very recently was it discovered that classical information can be sent at rates exceeding the long-conjectured Holevo bound.This project will attempt to develop new methods for reliable quantum communication and computation in the presence of noise. First, the research will push the capabilities and boundaries of quantum error-correction techniques, both by extending and delineating the types of correctable errors, and by determining the scenarios under which such error correction is or is not possible. The second goal is to develop the deep but heretofore largely unexplored connections between quantum codes, entanglement, and many-body physics, complexity theory, cryptography and high-dimensional geometry. The objective is to advance our understanding both of quantum codes as well as the related areas of mathematics, physics and computer science. Finally the team will seek to elucidate the subtle differences between quantum communication and its closest classical analog---private communication.This research endeavors to contribute definitively to realistic embodiments of large-scale quantum computers, which would dramatically improve mankind's ability to process and communicate information. And the research program itself is deeply interdisciplinary, bringing together physicists, computer scientists and mathematicians from industry and academia, and training students and postdocs.