Sequentially witnessing entanglement by independent observer pairs

Abstract

This study investigates measurement strategies in a scenario where multiple pairs of Alices and Bobs independently and sequentially observe entangled states. The aim is to maximize the number of observer pairs $(A_k,B_l)$ that can witness entanglement. Prior research has demonstrated that arbitrary pairs $(A_k,B_k)$ ($k\le n$) can observe entanglement in all pure entangled states and a specific class of mixed entangled states [Phys. Rev. A 106 032419 (2022)]. However, it should be noted that other pairs $(A_k,B_l)$ with $(k\ne l\le n)$ may not observe entanglement using the same strategy. Moreover, a novel strategy is presented, enabling every pair of arbitrarily many Alices and Bobs to witness entanglement regardless of the initial state being a Bell state or a particular class of mixed entangled states. These findings contribute to understanding measurement strategies for maximizing entanglement observation in various contexts.

arXiv comment11 pages, 2 figures

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• Quantum Correlation Sharing: A Review On Recent Progress From Nonlocality To Other Non-Classical Correlations
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