Thus, any function which qualifies and quantifies entanglement has to be non-increasing under LOCC. We introduce two classes of operational entanglement measures, i.e. the source and accessible entanglement. Whereas the source entanglement measures from how many states the state of interest can be obtained via LOCC, the accessible entanglement measures how many states can be reached via LOCC from the state at hand. We consider here pure bipartite as well as multipartite states and derive explicit formulae for these measures.
Moreover, we apply a state-conversion based
characterization of the mode-entanglement of Gaussian fermionic states (GFS).
More precisely, we derive a standard form of mixed n-mode n-partite GFS up to
Gaussian local unitaries and show that there exist no non-trivial Gaussian LOCC
transformations among pure states. Thus, we investigate the richer classes of
Gaussian stochastic and fermionic LOCC. This allows us to show how to identify
the maximally entangled set (MES) of GFS, which is the multipartite
generalization of the bipartite maximally entangled state.