Entanglement and statistical independence for mixed quantum states

CHRISTOF WETTERICH

Mostafa Mansour, Y. Hassouni

In this paper, we quantify the amount of entanglement of bipartite mixed states represented by a statistical mixture of the more general type of two-qubit non-orthogonal states of the form: [Formula: see text], constructed by linearly independent spin coherent states. We use the concurrence as a measure of entanglement and we study its behavior in terms of the amplitudes of SU(2) coherent states.

Eric Brunner, Aaron Xie, Gabriel Dufour +1 more

We develop a statistical framework, based on a manifold learning embedding, to extract relevant features of multipartite entanglement structures of mixed quantum states from the measurable correlation data of a quantum computer. We show that the statistics of the measured correlators contains sufficient information to characterise the entanglement, and to quantify the mixedness of the state of the computer's register. The transition to the maximally mixed regime, in the embedding space, displays a sharp boundary between entangled and separable states. Away from this boundary, the multipartite entanglement structure is robust to finite noise.

Dharmaraj Ramachandran, Aditya Dubey, Subrahmanyam S. G. Mantha +1 more

Animesh Datta, Steven T. Flammia, Carlton M. Caves +1 more

Christopher C. Gerry, Richard J. Birrittella, Paul M. Alsing +2 more

The quantum interference effects of mixing the most non-classical states of light, number states, with the most classical-like of pure field states, the coherent state, are investigated. We demonstrate how the non-classicality of a single photon when mixed with a coherent field can transform the statistical properties of the output and further demonstrate that the entanglement of the output is independent of the coherent state amplitude.This article is part of the theme issue 'The quantum theory of light'.