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中国物理学会期刊

多体系统中相干资源的一般化理论

CSTR: 32037.14.aps.68.20190966

General resource theory of quantum coherence in multipartite system

CSTR: 32037.14.aps.68.20190966
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  • 量子相干理论是一类重要的量子资源理论, 其自由操作是各种类型的非相干操作. 在单体相干资源理论中, 最大相干态是最重要的量子资源态, 它被定义为在非相干操作下可以转化为任何其他纯态的量子态. 但是, 这一情形在多体系统中发生了巨大改变: 不仅在有些相干度量下不存在唯一的最大相干态, 而且在有些非相干操作下几乎所有纯的相干多体态都不可比较(非相干操作下, 量子态之间的转换几乎不可能). 为了解决这一问题, 把非相干操作的定义扩展为一种不能产生相干的量子操作, 即研究一般化的相干资源理论. 具体地说, 基于量子资源是否来源于多体相干或者真的多体相干研究两类可能的量子资源理论框架, 并且指出在这些理论框架下存在合理的偏序关系(每个纯态都可在非相干操作下转换为相干度更弱的纯态). 另外, 还证明了真的多体相干资源理论下存在唯一的最大相干态.

     

    The theory of quantum coherence is an important kind of quantum resource theory, and its free operations are various kinds of incoherent operations. In the single-system coherence resource theory, the maximally coherent state is the most important quantum resource state, and it can turn into a quantum state of any other pure state. However, the situation is quite different from multipartite quantum systems: not only does no-go theorem forbidding the existence of a unique maximally coherent state exist there, but almost all pure multipartite coherent states are incomparable (i.e., some incoherent operation transformations among them are almost never possible). In order to cope with this problem, we consider general coherent resource theories in which we relax the traditional incoherent operations to operations that do not create coherence. Specifically, we consider two possible theories, depending on whether resources correspond to bipartite coherence or genuinely multipartite coherent states (each subsystem is coherent): one is the theory in which bipartite coherence states are considered as a resource and the free operations are bipartite incoherent preservation and the other is the theory that involves genuinely multipartite coherent states and fully incoherent operations. These ideas come from the research by Contreras-Tejada et al. (Phys. Rev. Lett. 122 120503), where the alternative entanglement resource theories were considered through relaxing the class of local operations and classical communication (LOCC) to operations that do not create entanglement, and they considered two possible theories depending on whether resources correspond to the multipartite entangled or genuinely multipartite entangled (GME) states. Furthermore, we show that there exists meaningful partial order (i.e. each pure state is transformable to a more weakly coherent pure state) in these two theory frames. Finally, we prove that the genuine multipartite coherent resource theory has a unique maximally coherent state (i.e. it can be transformed into any other state by the allowed free operations). Our results cover a wide class of coherent resource theories due to the free operations we introduced, and the discussion is solidified by important examples, such as entanglement, superposition, asymmetry, et al. And, how to establish the relations between these two kinds of multipartite coherent states, quantum discords and entanglements is also an interesting problem.

     

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