Molecular Magnetism and Quantum Information

Kevin Van Hoogdalem, Dimitrije Stepanenko, Daniel Loss

Anonymous

Filippo Troiani

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.

Barbara Goss Levi

By finding a way to reduce decoherence in relatively dense collections of tiny molecular magnets, researchers have enhanced their prospects as carriers of quantum information.

Amit Tribedi

Genuine quantumness present in quantum systems is the resource for implementing quantum information and computation protocols which can outperform the classical counterparts. These quantumness measures encompass non-local ones known as quantum entanglement (QE) and quantum information theoretic ones, e.g. quantum discord (QD). In this paper, some well-known measures of QE and QD have been studied in two wheel-like frustrated molecular magnetic systems, with special emphasis on the survival of the measures in the thermal states. A molecular magnetic system similar to the first one (with half-integer spins ) has already been synthesised using coordination chemistry, and the other is hypothetical, where the dominant interaction is the spin–spin exchange interaction. Exact numerical diagonalisation methods have been used. Some non-trivial features, like nonmonotonicity of threshold temperatures with external magnetic field, persistence of multipartite entanglement and QD over bipartite entanglement, have been found. The measures, being operational ones, can be used to realise the resource of quantumness in experiments.

Sergey Shinkevich