Understanding Entanglement as a Resource for Quantum Information Processing

Jozef Gruska

Beatrix C. Hiesmayr, Christopher Popp, Tobias C. Sutter

Bound entanglement is a special form of quantum entanglement that cannot be used for distillation, i.e. the local transformation of copies of arbitrarily entangled states into a smaller number of approximately maximally entangled states. Implying an inherent irreversibility of quantum resources, this phenomenon highlights the gaps in our current theory of entanglement. This review provides a comprehensive exploration of the key findings on bipartite bound entanglement. We focus on systems of finite dimensions, an area of high relevance for many quantum information processing tasks. We elucidate the properties of bound entanglement and its interconnections with various facets of quantum information theory and quantum information processing. The paper highlights areas where our understanding of bound entangled states, particularly in their detection and characterization, remains underdeveloped. By highlighting the need for further research into this phenomenon and underscoring relevant open questions, this paper invites researchers to unravel its relevance for our understanding of entanglement in Nature and how this resource can most effectively be used for applications in quantum technology.

Fumiaki Morikoshi

Entanglement, a weird quantum correlation between separate physical systems, is an indispensable resource for quantum information processing. As with other physical resources, the key to understanding its full potential is to quantify it. In this paper, I review our recent insights into the quantification of entanglement based on the operational notion of accessibility between physical states. In particular, I show that the partially ordered structure of mixed entangled states underlies the non-uniqueness of their entanglement measure.

Samuel L. Braunstein

Benoît Vermersch

Michele Caponigro

We argue, from epistemological point of view, the relationship between quantum entanglement and non-locality in quantum mechanics. The questions of how to quantify entanglement and non-locality and the need to clarify the relationship between them are important not only conceptually, but also practically, insofar as entanglement and non-locality seem to be different resources for the performance of quantum information processing tasks. Quantum information science is in the process of transforming our understanding of both QM and information theory.