Quantum transport and the phase space structure of the Wightman functions

Understand

We study the phase space structure of exact quantum Wightman functions in spatially homogeneous, temporally varying systems.

• In addition to the usual mass shells, the Wightman functions display additional coherence shells around zero frequency $k_0=0$, which carry the information of the local quantum coherence of particle-antiparticle pairs.
• We find also other structures, which encode non-local correlations in time, and discuss their role and decoherence.
• We give a simple derivation of the cQPA formalism, a set of quantum transport equations, that can be used to study interacting systems including the local quantum coherence.