论文标题
量子平均状态比您想象的要好：计算状态的快速算法使平均富达最大化
Quantum mean states are nicer than you think: fast algorithms to compute states maximizing average fidelity
论文作者
论文摘要
富达可以说是量子科学中最受欢迎的优点人物。但是，其许多属性仍然未知。在这项工作中，我们解决了对量子状态的任意有限综合并得出新的上限的开放问题，即最大化平均忠诚度。我们首先构建了一个半决赛程序，其最佳值是最大平均保真度，然后得出固定点算法，将收敛到最佳状态。定点算法在数值运行时优于半决赛程序。我们还得出了近距离状态的表达式，这些状态更易于计算和上限和下限，以获得最大平均保真度，当合奏通勤中的所有状态中的所有状态都确切。最后，我们讨论了我们的结果如何解决贝叶斯量子断层扫描中的一些开放问题。
Fidelity is arguably the most popular figure of merit in quantum sciences. However, many of its properties are still unknown. In this work, we resolve the open problem of maximizing average fidelity over arbitrary finite ensembles of quantum states and derive new upper bounds. We first construct a semidefinite program whose optimal value is the maximum average fidelity and then derive fixed-point algorithms that converge to the optimal state. The fixed-point algorithms outperform the semidefinite program in terms of numerical runtime. We also derive expressions for near-optimal states that are easier to compute and upper and lower bounds for maximum average fidelity that are exact when all the states in the ensemble commute. Finally, we discuss how our results solve some open problems in Bayesian quantum tomography.
