Activities per year
Abstract
We propose and develop a measurement scheme for quantum field theory (QFT) in curved spacetimes, in which the QFT of interest, the ``system'', is dynamically coupled to another, the ``probe'', in a compact spacetime region. Measurements of observables in the probe system then serve as proxy measurements of observables in the system, under a correspondence which depends also on a preparation state of the probe theory. All our constructions are local and covariant, and the conditions may be stated abstractly in the framework of algebraic quantum field theory (AQFT). The induced system observables corresponding to probe observables may be localized in the causal hull of the coupling region and are typically less sharp than the probe observable, but more sharp than the actual measurement on the coupled theory. A formula is given for the postselected system state, conditioned on measurement outcomes, which is closely related to the notion of an instrument as introduced by Davies and Lewis. This formula has the important property that individual measurements form consistent composites, provided that their coupling regions can be causally ordered and a certain causal factorisation property holds for the dynamics; the composite is independent of the causal order chosen if more than one exists. The general framework is amenable to calculation, as is shown in a specific example. This contribution reports on joint work with R.~Verch, arXiv:1810.06512.
Original language  English 

Title of host publication  Progress and Visions in Quantum Theory in View of Gravity: Bridging foundations of physics and mathematics 
Editors  Felix Finster, Domenico Giulini, Johannes Kleiner, Jürgen Tolksdorf 
Place of Publication  Cham 
Publisher  Birkhauser 
Number of pages  15 
ISBN (Electronic)  9783030389413 
ISBN (Print)  9783030389406 
Publication status  Published  2020 
Activities
 3 Invited talk

Measurement schemes in local quantum physics
Chris Fewster (Invited speaker)
18 Jun 2020Activity: Talk or presentation › Invited talk

Measurement schemes for quantum field theory in curved spacetimes
Chris Fewster (Invited speaker)
9 Apr 2020Activity: Talk or presentation › Invited talk

Local measurement schemes for quantum field theory in curved spacetimes
Chris Fewster (Invited speaker)
31 Oct 2018Activity: Talk or presentation › Invited talk