  We present observable lower bounds for several bipartite entanglement
measures including entanglement of formation, geometric measure of
entanglement, concurrence, convex-roof extended negativity, and G-concurrence.
The lower bounds facilitate estimates of these entanglement measures for
arbitrary finite-dimensional bipartite states. Moreover, these lower bounds can
be calculated analytically from the expectation value of a single observable.
Based on our results, we use several real experimental measurement data to get
lower bounds of entanglement measures for these experimentally realized states.
In addition, we also study the relations between entanglement measures.

Quantum Physics