State-average calculations based on a mixture of states are increasingly being exploited across chemistry and physics as versatile procedures for addressing excitations of quantum many-body systems. If not too many states should need to be addressed, calculations performed on individual states are also a common option. Here we show how the two approaches can be merged into one method, dealing with a generalized yet single pure state. Implications in electronic structure calculations are discussed and for quantum computations are pointed out.

中文翻译：

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通过纯化系综激发量子多体系统：一种基于酉耦合集群的方法

基于状态混合的状态平均计算正越来越多地在化学和物理学中被用作解决量子多体系统激发的通用程序。如果不需要处理太多的状态，对单个状态进行计算也是一种常见的选择。在这里，我们展示了如何将这两种方法合并为一种方法，处理一个通用但单一的纯状态。讨论了电子结构计算中的含义，并指出了量子计算。