Activation of genuine multipartite entanglement: beyond the single-copy paradigm of entanglement characterisation

Activation of genuine multipartite entanglement: beyond the single-copy paradigm of entanglement characterisation

Seminar author:Simon Morelli

Event date and time:09/23/2021 04:00:pm

Event location:https://us02web.zoom.us/j/83410362610?pwd=VkJrVENrTmRSL1NBU3BZeXBmS1RQdz09

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Entanglement shared among multiple parties presents complex challenges for the characterisation of different types of entanglement. One of the most basic insights is the fact that some mixed states can feature entanglement across every possible cut of a multipartite system, yet can be produced via a mixture of partially separable states. To distinguish states that genuinely cannot be produced from mixing partially separable states, the term genuine multipartite entanglement was coined. All these considerations originate in a paradigm where only a single copy of the state is distributed and locally acted upon. In contrast, advances in quantum technologies prompt the question of how this picture changes when multiple copies of the same state become locally accessible. Here we show that multiple copies unlock genuine multipartite entanglement from partially separable states, even from undistillable ensembles, and even more than two copies can be required to observe this effect. With these findings, we characterise the notion of partial separability in the paradigm of multiple copies and conjecture a strict hierarchy of activatable states and an asymptotic collapse of hierarchy. https://arxiv.org/abs/2106.01372