6533b825fe1ef96bd12833dd
RESEARCH PRODUCT
Wick Theorem for General Initial States
Gianluca StefanucciGianluca StefanucciR. Van Leeuwensubject
High Energy Physics - Theoryta114Statistical Mechanics (cond-mat.stat-mech)Numerical techniqueBoundary problemFOS: Physical sciencesCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsSettore FIS/03 - Fisica della Materiasymbols.namesakeWick's theoremHigh Energy Physics - Theory (hep-th)Quantum mechanicsNo-go theoremWick rotationsymbolsGreen's theoremQuantum statistical mechanicsBrouwer fixed-point theoremCondensed Matter - Statistical MechanicsMathematical physicsMathematicsdescription
We present a compact and simplified proof of a generalized Wick theorem to calculate the Green's function of bosonic and fermionic systems in an arbitrary initial state. It is shown that the decomposition of the non-interacting $n$-particle Green's function is equivalent to solving a boundary problem for the Martin-Schwinger hierarchy; for non-correlated initial states a one-line proof of the standard Wick theorem is given. Our result leads to new self-energy diagrams and an elegant relation with those of the imaginary-time formalism is derived. The theorem is easy to use and can be combined with any ground-state numerical technique to calculate time-dependent properties.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2012-01-01 |