Simplified quantum process tomography
Simplified quantum process tomography
复制标题
简化的量子过程断层扫描
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
R L Kosut
中科院分区：
文献类型：
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作者：
M. Branderhorst;J. Nunn;I A Walmsley;R L Kosut
我们提出并实验评估了一种量子过程层析成像方法，它完全消除了困扰标准方法的标度问题。这种简化的关键是纳入了产生动力学所涉及的物理相互作用类别的先验知识，这将问题简化为参数估计问题。这允许使用有效的凸方法来解决问题的一部分，当再加上对某些参数的约束时，允许从实验数据中确定Krauss算子的全局最优估计。参数化图提供了更多的优点：它允许包含环境的混合状态以及系统和环境之间的一些初始关联，这两者都是在系统激励远离热平衡之后的常见物理情况。尽管这种方法不是通用的，但在它有效的情况下，它会返回一组完整的正映射，用于始终描述量子系统的动态演化。
We propose and evaluate experimentally an approach to quantum process tomography that completely removes the scaling problem plaguing the standard approach. The key to this simplification is the incorporation of prior knowledge of the class of physical interactions involved in generating the dynamics, which reduces the problem to one of parameter estimation. This allows part of the problem to be tackled using efficient convex methods, which, when coupled with a constraint on some parameters, allows globally optimal estimates for the Krauss operators to be determined from experimental data. Parameterizing the maps provides further advantages: it allows the incorporation of mixed states of the environment as well as some initial correlation between the system and environment, both of which are common physical situations following excitation of the system away from thermal equilibrium. Although the approach is not universal, in cases where it is valid it returns a complete set of positive maps for the dynamical evolution of a quantum system at all times.