Unitary channel discrimination beyond group structures: Advantages of sequential and indefinite-causal-order strategies
Unitary channel discrimination beyond group structures: Advantages of sequential and indefinite-causal-order strategies
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DOI：
10.1063/5.0075919
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发表时间：
2022-04-01
影响因子：
1.3
通讯作者：
Quintino, Marco Tulio
中科院分区：
文献类型：
--
作者：
Bavaresco, Jessica;Murao, Mio;Quintino, Marco Tulio
对于仅涉及单一通道的最小误差通道辨别任务，我们表明顺序策略可能优于并行策略。此外，我们表明，涉及不确定的因果顺序的一般策略也有利于这项任务。然而，对于区分一组均匀分布的单一通道，形成一个组的任务，我们表明，平行的策略，确实是最佳的，即使相比，一般的策略。我们还表明，基于量子开关的策略不能优于顺序策略在酉信道的歧视。最后，我们推导出一个绝对上限的最大概率成功地区分任何一组酉信道与任何数量的副本，最一般的战略，适合于信道歧视。我们的界限是紧的，因为它是饱和的酉通道组形成一个组k-设计。由AIP Publishing独家授权出版。
For minimum-error channel discrimination tasks that involve only unitary channels, we show that sequential strategies may outperform the parallel ones. Additionally, we show that general strategies that involve indefinite causal order are also advantageous for this task. However, for the task of discriminating a uniformly distributed set of unitary channels that forms a group, we show that parallel strategies are, indeed, optimal, even when compared to general strategies. We also show that strategies based on the quantum switch cannot outperform sequential strategies in the discrimination of unitary channels. Finally, we derive an absolute upper bound for the maximal probability of successfully discriminating any set of unitary channels with any number of copies for the most general strategies that are suitable for channel discrimination. Our bound is tight since it is saturated by sets of unitary channels forming a group k-design. Published under an exclusive license by AIP Publishing.