Feynman Diagram Technique

J. Schirmer

Henrik Bruus, Karsten Flensberg

Abstract It is in the case of interacting particles and fields that the power of quantum field theory and Feynman diagrams really comes into play. In this chapter, we develop the Feynman diagram technique for a system of fermions with pair interactions. The primary example we will work with is a gas of fermions interacting through Coulomb interactions, but the technique is derived in a more general framework. In general, the Hamiltonian has two parts H = H 0 + W .

Radi A. Jishi

Introduction to the application of Feynman diagram techniques for researchers and advanced undergraduate students in condensed matter theory and many-body physics.

Benjamin Bähr, Boris Lemmer, Rina Piccolo

Haider R. Zaidi

The squeezing spectrum of a parametric amplifier, with a quantized pump field, is calculated using the Feynman-diagram technique. The results of the existing theories are recovered. The connection with the theory of superconductivity becomes transparent in this approach.