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arXiv · 2209.08746

Gaussian entanglement witness and refined Werner-Wolf criterion for continuous variables

Xiao-yu Chen·Maoke Miao·Rui Yin·Jiantao Yuan
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Abstract

We use matched quantum entanglement witnesses to study the separable criteria of continuous variable states. The witness can be written as an identity operator minus a Gaussian operator. The optimization of the witness then is transformed to an eigenvalue problem of a Gaussian kernel integral equation. It follows a separable criterion not only for symmetric Gaussian quantum states, but also for non-Gaussian states prepared by photon adding to or/and subtracting from symmetric Gaussian states. Based on Fock space numeric calculation, we obtain an entanglement witness for more general two-mode states. A necessary criterion of separability follows for two-mode states and it is shown to be necessary and sufficient for a two mode squeezed thermal state and the related two-mode non-Gaussian states. We also connect the witness based criterion with Werner-Wolf criterion and refine the Werner-Wolf criterion.

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Xiao-yu Chen, Maoke Miao, Rui Yin, Jiantao Yuan. 2022-09-19. Gaussian entanglement witness and refined Werner-Wolf criterion for continuous variables. https://doi.org/10.1103/physreva.107.022410

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