Verification of bound entanglement by entanglement quasiprobabilities. (arXiv:1708.03109v1 [quant-ph])

The verification of quantum entanglement under the influence of realistic
noise and decoherence is crucial for the development of quantum technologies.
Unfortunately, a full entanglement characterization is generally not possible
with most entanglement criteria such as entanglement witnesses or the partial
transposition criterion. In particular, so called bound entanglement cannot be
certified via the partial transposition criterion. We present here the full
entanglement verification of dephased qubit and qutrit Werner states via
entanglement quasiprobabilities. Remarkably, we are able to reveal bound
entanglement for noisy-mixed states in the qutrit case. This example
demonstrates the strength of the entanglement quasiprobabilities for verifying
the full entanglement of quantum sates suffering from noise.

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