Quantum resource studied from the perspective of quantum state superposition

Abstract

Quantum resources,such as discord and entanglement, are crucial in quantum information processing. In this paper, quantum resources are studied from the aspect of quantum state superposition. We define the local superposition (LS) as the superposition between basis of single part, and nonlocal superposition (NLS) as the superposition between product basis of multiple parts. For quantum resource with nonzero LS, quantum operation must be introduced to prepare it, and for quantum resource with nonzero NLS, nonlocal quantum operation must be introduced to prepare it. We prove that LS vanishes if and only if the state is classical and NLS vanishes if and only if the state is separable. From this superposition aspect, quantum resources are categorized as superpositions existing in different parts. These results are helpful to study quantum resources from a unified frame. PACS numbers: 03.67.-a, 03.67.Mn,03.65.Ta II. LOCAL SUPERPOSITION IN BIPARTITE SYSTEMWhen considering a quantum state with superposition in the {|0 , |1 } basis, |ψ = α |0 + β |1 , the coherence of the state can be defined as C({|0 , |1 }) = 2 |α| |β| =