We introduce a Feynman diagram calculus for quantum stochastic fields and show that from the weak coupling limit of a Bose quantum field reservoir in a Gaussian state one obtains a quantum stochastic field process which has extended Wigner statistics. That is, we calculate explicitly the moments using the diagram rules and show that only moments corresponding to non-crossing diagrams are non-trivial. We further give the physical mechanism underlying this fact; namely the combination of momentum conservation (arising from the correct treatment of the full responsive interaction) and the mass-shell energy conservation for the virtual (stochastic) reservoir quanta. In our analysis we introduce a volume cut-off initially for the system particle to discretize its energy spectrum and then take the weak coupling limit. The individual noise fields associated with energy state transitions were Gaussian however, when the volume cut-off is then removed and we recover the noise correlations. Thus for this problem the removal of the cut-off and the weak coupling limit are in fact interchangeable.We introduce a Feynman diagram calculus for quantum stochastic fields and show that from the weak coupling limit of a Bose quantum field reservoir in a Gaussian state one obtains a quantum stochastic field process which has extended Wigner statistics. That is, we calculate explicitly the moments using the diagram rules and show that only moments corresponding to non-crossing diagrams are non-trivial. We further give the physical mechanism underlying this fact; namely the combination of momentum conservation (arising from the correct treatment of the full responsive interaction) and the mass-shell energy conservation for the virtual (stochastic) reservoir quanta. In our analysis we introduce a volume cut-off initially for the system particle to discretize its energy spectrum and then take the weak coupling limit. The individual noise fields associated with energy state transitions were Gaussian however, when the volume cut-off is then removed and we recover the noise correlations. Thus for this problem the removal of the cut-off and the weak coupling limit are in fact interchangeable.

Journal of Physics A Mathematical and GeneralFeb 27, 19981 citation

Interactions and Feynman Diagrams

Theoretical and mathematical physicsNov 29, 20080 citations

Determinant Monte Carlo for irreducible Feynman diagrams in the strongly correlated regime

Fedor Šimkovic, Evgeny Kozik

We develop a numerically exact method for the summation of irreducible Feynman diagrams for fermionic self-energy in the thermodynamic limit. The technique, based on the diagrammatic determinant Monte Carlo and its recent extension to connected diagrams, allows us to reach high $(\ensuremath{\sim}10)$ orders of the weak-coupling expansion for the self-energy of the two-dimensional Hubbard model. Access to high orders reveals a nontrivial analytic structure of the self-energy and enables its controlled reconstruction with arbitrary momentum resolution in the nonperturbative regime of essentially strong correlations, which has recently been reached with ultracold atoms in optical lattices.We develop a numerically exact method for the summation of irreducible Feynman diagrams for fermionic self-energy in the thermodynamic limit. The technique, based on the diagrammatic determinant Monte Carlo and its recent extension to connected diagrams, allows us to reach high $(\ensuremath{\sim}10)$ orders of the weak-coupling expansion for the self-energy of the two-dimensional Hubbard model. Access to high orders reveals a nontrivial analytic structure of the self-energy and enables its controlled reconstruction with arbitrary momentum resolution in the nonperturbative regime of essentially strong correlations, which has recently been reached with ultracold atoms in optical lattices.

arXiv:1712.10001Physical review. B./Physical review. BSep 4, 201957 citations

Perturbation Theory and Feynman Diagrams

Michael Rudolf Vogl

UNITEXT for physicsOct 7, 20260 citations

On the weak coupling limit problem

Luigi Accardi, A. Frigerio, Yun Gang Lu

Lecture notes in mathematicsJan 1, 198915 citations

Determinant Monte Carlo for irreducible Feynman diagrams

Fedor Šimkovic, Evgeny Kozik

We introduce a numerically exact method for efficient summation of irreducible Feynman diagrams for the fermionic self-energy in the thermodynamic limit. The technique, based on the Diagrammatic Determinant Monte Carlo, allows us to reach unprecedentedly high ( $\sim 10$ ) orders of the weak-coupling expansion for the self-energy of the two-dimensional Hubbard model. Access to high orders reveals a non-trivial analytic structure of the self-energy and enables its controlled reconstruction with arbitrary momentum resolution in the non-perturbative regime of essentially strong correlations, which has recently been reached with ultracold atoms in optical lattices.We introduce a numerically exact method for efficient summation of irreducible Feynman diagrams for the fermionic self-energy in the thermodynamic limit. The technique, based on the Diagrammatic Determinant Monte Carlo, allows us to reach unprecedentedly high ($\sim 10$) orders of the weak-coupling expansion for the self-energy of the two-dimensional Hubbard model. Access to high orders reveals a non-trivial analytic structure of the self-energy and enables its controlled reconstruction with arbitrary momentum resolution in the non-perturbative regime of essentially strong correlations, which has recently been reached with ultracold atoms in optical lattices.

Dec 28, 20170 citations

\sim 10

) orders of the weak-coupling expansion for the self-energy of the two-dimensional Hubbard model. Access to high orders reveals a non-trivial analytic structure of the self-energy and enables its controlled reconstruction with arbitrary momentum resolution in the non-perturbative regime of essentially strong correlations, which has recently been reached with ultracold atoms in optical lattices.