Article Dans Une Revue Physical Review A Année : 2021

Entanglement for any definition of two subsystems

Résumé

The notion of entanglement of quantum states is usually defined with respect to a fixed bipartition. Indeed, a global basis change can always map an entangled state to a separable one. The situation is, however, different when considering a set of states. In this work we define the notion of an “absolutely entangled set” of quantum states: for any possible choice of global basis, at least one of the states in the set is entangled. Hence, for all bipartitions, i.e., any possible definition of the subsystems, the set features entanglement. We present examples of such sets, including sets with minimal size. Moreover, we propose a quantitative measure for absolute set entanglement. To lower bound this quantity, we develop a method based on polynomial optimization to perform convex optimization over unitaries, which is of independent interest.

Dates et versions

hal-04207886 , version 1 (14-09-2023)

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Citer

Yu Cai, Baichu Yu, Pooja Jayachandran, Nicolas Brunner, Valerio Scarani, et al.. Entanglement for any definition of two subsystems. Physical Review A, 2021, 103 (5), pp.052432. ⟨10.1103/PhysRevA.103.052432⟩. ⟨hal-04207886⟩
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