Abstract
Any bipartite entanglement witness can be written as , where is a quantum state, is the identity matrix, and is a non-negative number. We present a general method to extend the given entanglement witness to multipartite cases via purification, partial purification, and direct tensor of the quantum state . Our methods extend but leave the parameter untouched. This is very valuable since the parameter is generally not easy to compute.
- Received 9 May 2014
DOI:https://doi.org/10.1103/PhysRevA.90.022312
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