Relating relative Rényi entropies and Wigner-Yanase-Dyson skew information to generalized multiple quantum coherences (2002.11177v2)

Abstract: Quantum coherence is a crucial resource for quantum information processing. By employing the language of coherence orders largely applied in NMR systems, quantum coherence has been currently addressed in terms of multiple quantum coherences (MQCs). Here we investigate the $\alpha$-MQCs, a novel class of multiple quantum coherences which is based on $\alpha$-relative purity, an information-theoretic quantifier analogous to quantum fidelity and closely related to R\'{e}nyi relative entropy of order $\alpha$. Our framework enables linking $\alpha$-MQCs to Wigner-Yanase-Dyson skew information (WYDSI), an asymmetry monotone finding applications in quantum thermodynamics and quantum metrology. Furthermore, we derive a family of bounds on $\alpha$-MQCs, particularly showing that $\alpha$-MQC define a lower bound to quantum Fisher information (QFI). We illustrate these ideas for quantum systems described by single-qubit states, two-qubit Bell-diagonal states, and a wide class of multiparticle mixed states. Finally, we investigate the time evolution of the $\alpha$-MQC spectrum and the overall signal of relative purity, by simulating the time reversal dynamics of a many-body all-to-all Ising Hamiltonian and comment on applications to physical platforms such as NMR systems, trapped ions, and ultracold atoms.