arXiv 1102.19182011-02-09quant-ph

连续变量和原子系综的量子信息处理

Quantum Information Processing with Continuous Variables and Atomic Ensembles

Marcin Zwierz

备注：: PhD Thesis, University of Sheffield, UK (January 2011), 142 pages, 21 figures

摘要：

本文介绍了量子信息理论中的三个不同结果。第一个结果解决了量子精密测量的理论基础。海森伯极限被认为是量子精密测量的极限，它为在任何可能的测量中给定一定量的资源可以测量物理量的精确程度设定了一个下限。然而，最近提出了几种测量方法，其中海森堡极限似乎被超越了。这导致了一个广泛的辩论的问题，如何灵敏度尺度与物理资源和计算资源中使用的估计程序。在这里，我们调和相关资源的物理定义与量子网络查询复杂性方面的信息理论缩放。这导致了一个新的和最终的海森堡极限，适用于所有可能的测量程序。第二个结果揭示了连续变量量子系统上的量子精密测量和Deutsch-Jozsa算法之间的密切关系。在这里，我们开发了一个一般的程序，其特征在于由两个参数，统一的参数估计和Deutsch-Jozsa算法。该程序估计一个未知参数的值与海森堡有限的精度或解决Deutsch-Jozsa问题在一个单一的运行，而不使用任何纠缠。第三个结果说明了如何有效地利用控制光和物质相互作用的物理原理来为（单向）量子计算机创建计算资源。更具体地说，我们从理论上证明了一个计划的基础上原子系综和偶极封锁机制产生所谓的集群状态在一个单一的步骤。这个过程比任何已知的鲁棒概率纠缠操作都要有效得多。

英文摘要：

This thesis presents three different results in quantum information theory. The first result addresses the theoretical foundations of quantum metrology. The Heisenberg limit considered as the ultimate limit in quantum metrology sets a lower bound on how precisely a physical quantity can be measured given a certain amount of resources in any possible measurement. Recently, however, several measurement procedures have been proposed in which the Heisenberg limit seemed to be surpassed. This led to an extensive debate over the question how the sensitivity scales with the physical resources and the computational resources that are used in estimation procedures. Here, we reconcile the physical definition of the relevant resources with the information-theoretical scaling in terms of the query complexity of a quantum network. This leads to a novel and ultimate Heisenberg limit that applies to all conceivable measurement procedures. The second result reveals a close relationship between quantum metrology and the Deutsch-Jozsa algorithm over continuous-variable quantum systems. Here, we develop a general procedure, characterized by two parameters, that unifies parameter estimation and the Deutsch-Jozsa algorithm. The procedure estimates a value of an unknown parameter with Heisenberg-limited precision or solves the Deutsch-Jozsa problem in a single run without the use of any entanglement. The third result illustrates how physical principles that govern interaction of light and matter can be efficiently employed to create a computational resource for a (one-way) quantum computer. More specifically, we demonstrate theoretically a scheme based on atomic ensembles and the dipole blockade mechanism for generation of the so-called cluster states in a single step. This procedure is significantly more efficient than any known robust probabilistic entangling operation.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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