Naive attempts to put together relativity and quantum measurements lead to signaling between space-like separated regions. In QFT, these are known as impossible measurements.

Open quantum systems bearing transport with non-commuting conserved quantities (charges) offer the possibility to study the interplay between quantum and thermal effects. A general theory for such non-abelian transport is, however, unavailable.

The Feynman-Vernon influence functional (also known as the decoherence functional, or the Schwinger-Keldysh path integral) is a tool that appears in many forms across different areas of theoretical physics, ranging from non-equilibrium quantum field…

The theory of decoherence is arguably among the greatest advances in fundamental physics of the past forty years