Passing quantum correlations to qubits using any two-mode state

TL;DR

This paper establishes a formal connection between the properties of two-mode continuous variable entangled states and their ability to transfer entanglement to qubits, highlighting the advantages of Gaussian states and the impact of noise.

Contribution

It introduces a covariance matrix formalism for analyzing entanglement transfer, simplifying the process and including noise effects, and shows Gaussian states are generally more effective than non-Gaussian states for this purpose.

Findings

Gaussian states facilitate flexible entanglement transfer.

De-Gaussified states are rarely advantageous for transfer.

Entanglement transfer relations differ from resource state ordering.

Abstract

We draw an explicit connection between the statistical properties of an entangled two-mode continuous variable (CV) resource and the amount of entanglement that can be dynamically transferred to a pair of non-interacting two-level systems. More specifically, we rigorously reformulate entanglement transfer process by making use of covariance matrix formalism. When the resource state is Gaussian, our method makes the approach to the transfer of quantum correlations much more flexible than in previously considered schemes and allows the straightforward inclusion of the effects of noise affecting the CV system. Moreover, the proposed method reveals that the use of de-Gaussified two-mode states is almost never advantageous for transferring entanglement with respect to the full Gaussian picture, despite the entanglement in the non-Gaussian resource can be much larger than in its Gaussian counterpart. We can thus conclude that the entanglement-transfer map overthrows the "ordering" relations valid at the level of CV resource states.