Dephasing is a prominent noise mechanism that afflicts quantum information carriers, and it is one of the main challenges towards realizing useful quantum computation, communication, and sensing. Here we consider discrimination and estimation of bosonic dephasing channels, when using the most general adaptive strategies allowed by quantum mechanics. We reduce these difficult quantum problems to simple classical ones based on the probability densities defining the bosonic dephasing channels. By doing so, we rigorously establish the optimal performance of various distinguishability and estimation tasks and construct explicit strategies to achieve this performance. To the best of our knowledge, this is the first example of a non-Gaussian bosonic channel for which there are exact solutions for these tasks.

翻译：退相位是一种影响量子信息载体的显著噪声机制，也是实现实用量子计算、通信与传感的主要挑战之一。本文考虑在允许使用量子力学所允许的最通用自适应策略时，对玻色子退相位通道进行鉴别与估计的问题。我们将这些困难量子问题简化为基于定义玻色子退相位通道概率密度的经典问题。通过这一方法，我们严格确定了各类可区分性与估计任务的最优性能，并构建了实现该性能的显式策略。据我们所知，这是首个针对非高斯玻色子通道存在此类问题精确解的实例。