  We investigate the notion of "macroscopicity" in the case of large quantum
spin systems and provide two main results. First, we motivate the Fisher
information as a measure for the macroscopicity of quantum states. Second, we
compare the existing literature of this topic. We report on a hierarchy among
the measures and we conclude that one should carefully distinguish between
"macroscopic quantum states" and "macroscopic superpositions", which is a
strict subclass of the former.

Quantum Physics