Maximilian H. Ruep - Causality in Quantum Field Theory on a fixed Background

Thursday 10 Feb 2022, 10:00 → 11:00 Europe/Berlin

Abstract: Fixed, non-dynamical backgrounds, on which QFTs may be defined, come with their own causal structure; and while it is an axiom that spacelike separated observables of any QFT commute, it is still a non trivial question in what sense causality is incorporated in quantum field theory. Indeed, as an old protocol by Sorkin demonstrates, a priori perfectly reasonable local quantum operations (e.g, non-selective measurements) might still allow to superluminally signal. In this talk I will present a class of physically reasonable local and fully causal quantum operations for QFTs on fixed backgrounds. If time permits, I will indicate how they can be used to perform causal measurements of local observables.
This talk is based on joint work with H. Bostelmann.and C. J. Fewster.