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arXiv · 1903.08663

Entanglement negativity as a universal non-Markovianity witness

Jan Kolodynski·Swapan Rana·Alexander Streltsov
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Abstract

In order to engineer an open quantum system and its evolution, it is essential to identify and control the memory effects. These are formally attributed to the non-Markovianity of dynamics that manifests itself by the evolution being indivisible in time, a property which can be witnessed by a non-monotonic behavior of contractive functions or correlation measures. We show that by monitoring directly the entanglement behavior of a system in a tripartite setting it is possible to witness all invertible non-Markovian dynamics, as well as all (also non-invertible) qubit evolutions. This is achieved by using negativity, a computable measure of entanglement, which in the usual bipartite setting is not a universal non-Markovianity witness. We emphasize further the importance of multipartite states by showing that non-Markovianity cannot be faithfully witnessed by any contractive function of single qubits. We support our statements by an explicit example of eternally non-Markovian qubit dynamics, for which negativity can witness non-Markovianity at arbitrary time scales.

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Jan Kolodynski, Swapan Rana, Alexander Streltsov. 2019-12-10. Entanglement negativity as a universal non-Markovianity witness. https://doi.org/10.1103/physreva.101.020303

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