  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 complete detection of entanglement is performed in a
single run experiment. This approach is particularly important for experiments
where it is operationally difficult to prepare several copies of an unknown
quantum state and in this sense the introduced scheme in this work is superior
to the generally used entanglement witnesses that require a number of
experiments and preparation of copies of quantum state.
