The spin sector of charge-spin separated single mode quantum wires is studied, accounting for realistic microscopic electron-electron interactions. We utilize the ladder approximation (LA) to the interaction vertex and exploit thermodynamic relations to obtain spin velocities. Down to not too small carrier densities our results compare well with existing quantum Monte Carlo (QMC) data. Analyzing second-order diagrams we identify logarithmically divergent contributions as crucial which the LA includes but which are missed, for example, by the self-consistent Hartree-Fock approximation. Contrary to other approximations the LA yields a nontrivial spin conductance. Its considerably smaller computational effort compared to numerically exact methods, such as the QMC method, enables us to study overall dependences on interaction parameters. We identify the short distance part of the interaction to govern spin sector properties.The spin sector of charge-spin separated single mode quantum wires is studied, accounting for realistic microscopic electron-electron interactions. We utilize the ladder approximation (LA) to the interaction vertex and exploit thermodynamic relations to obtain spin velocities. Down to not too small carrier densities our results compare well with existing quantum Monte Carlo (QMC) data. Analyzing second-order diagrams we identify logarithmically divergent contributions as crucial which the LA includes but which are missed, for example, by the self-consistent Hartree-Fock approximation. Contrary to other approximations the LA yields a nontrivial spin conductance. Its considerably smaller computational effort compared to numerically exact methods, such as the QMC method, enables us to study overall dependences on interaction parameters. We identify the short distance part of the interaction to govern spin sector properties.

arXiv:cond-mat/0312296Physical Review BFeb 13, 20045 citations

The external-field approximation in quantum optics

R. Samson, A. Ben‐Reuven

Chemical Physics LettersDec 1, 19759 citations

Parquet dual fermion approach for the Falicov-Kimball model

Katharina Astleithner, Anna Kauch, T. Ribic +1 more

In the Falicov-Kimball model, a model for (annealed) disorder, we expect weak localization corrections to the optical conductivity. However, we get such weak localization effects only when employing a $pp$ -ladder approximation in the dual fermion approach. In the full parquet approach, these $pp$ contributions are suppressed by $ph$ -reducible diagrams. For the optical conductivity, we find that the $\overline{ph}$ channel yields the main contribution, even in the region where weak localization in the $pp$ ladder was indicated.In the Falicov-Kimball model, a model for (annealed) disorder, we expect weak localization corrections to the optical conductivity. However, we get such weak localization effects only when employing a $pp$-ladder approximation in the dual fermion approach. In the full parquet approach, these $pp$ contributions are suppressed by $ph$-reducible diagrams. For the optical conductivity, we find that the $\overline{ph}$ channel yields the main contribution, even in the region where weak localization in the $pp$ ladder was indicated.