Matched witness for multipartite entanglement

A witness of multipartite entanglement strata

We describe an entanglement witness for N -qubit mixed states based on the properties of N -point correlation functions. As the degree of violation increases beyond different threshold values, or strata, this witness can guarantee that no more than M qubits are separable from the rest of the state for any M 6 N , or that there is some genuine M-party or greater multipartite entanglement present...

Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing

In this paper we provide an operational method to detect multipartite entanglement in ensemble-based quantum computing. This method is based on the concept of entanglement witness. We decompose the entanglement witness for each class of multipartite entanglement into nonlocal operations in addition to local measurements. Individual single qubit measurements are performed simultaneously, hence c...

Experimental detection of multipartite entanglement using witness operators.

We present the experimental detection of genuine multipartite entanglement using entanglement witness operators. To this aim, we introduce a canonical way of constructing and decomposing witness operators so that they can be directly implemented with present technology. We apply this method to three- and four-qubit entangled states of polarized photons, giving experimental evidence that the con...

Title Genuine multipartite entanglement without multipartite correlations

Genuine Multipartite Entanglement without Multipartite Correlations.

Nonclassical correlations between measurement results make entanglement the essence of quantum physics and the main resource for quantum information applications. Surprisingly, there are n-particle states which do not exhibit n-partite correlations at all but still are genuinely n-partite entangled. We introduce a general construction principle for such states, implement them in a multiphoton e...