On the Use of Classical and Quantum Fisher Information in Molecular Magnetism

The present paper discusses the use of two information-theoretical quantities—namely, the classical and quantum Fisher information—in the context of molecular magnetism. These functions quantify the suitability of a given observable to the estimation of a physical parameter and provide the highest precision allowed by quantum mechanics in such an estimation process. The quantum Fisher information also quantifies the degree of macroscopicity of a quantum state. As illustrative examples of such applications, we compute the classical and quantum Fisher information of the Fe ${}_4$ molecular nanomagnet, used as a probe of an applied magnetic field or as a platform for generating Schrödinger cat states.