152 citations · 2.3k across the 94 of their papers we have counts for
40 papers · 1 filter
Coupled Proca theories: Green-hyperbolicity, quantization and applications to polarization measurement
Christopher J. Fewster, Christiane K. M. Klein
The Proca field describes a massive relativistic spin- particle and was originally formulated in Minkowski spacetime. Here we consider a variety of generalizations in globally h…
On the construction of Hadamard states from Feynman propagators
Christopher J. Fewster, Alexander Strohmaier
The Wightman two-point function of any Hadamard state of a linear quantum field theory determines a corresponding Feynman propagator. Conversely, however, a Feynman propagator dete…
Semi-local observables, edge modes and quantum reference frames in quantum electromagnetism: an algebraic approach
Christopher J. Fewster, Daan W. Janssen, Kasia Rejzner
Boundaries and corners of spacetime play a vital role in understanding physical concepts including entanglement entropy, the infrared problem in QFT and quantum gravity. Standard l…
Polarisation sets of Green operators for normally hyperbolic equations
Christopher J. Fewster
The polarisation set of a vector-valued distribution generalises the wavefront set and captures fibre-directional information about its singularities in addition to their phase spa…
Hadamard states for decomposable Green-hyperbolic operators
Christopher J. Fewster
Hadamard states were originally introduced for quantised Klein-Gordon fields and occupy a central position in the theory of quantum fields on curved spacetimes. Subsequently they h…
Quantum reference frames, measurement schemes and the type of local algebras in quantum field theory
Christopher J. Fewster, Daan W. Janssen, Leon Deryck Loveridge +2
We develop an operational framework, combining relativistic quantum measurement theory with quantum reference frames (QRFs), in which local measurements of a quantum field on a bac…
Measurement in Quantum Field Theory
Christopher J. Fewster, Rainer Verch
The topic of measurement in relativistic quantum field theory is addressed in this article. Some of the long standing problems of this subject are highlighted, including the incomp…
Modified Green-Hyperbolic Operators
Christopher J. Fewster
Green-hyperbolic operators - partial differential operators on globally hyperbolic spacetimes that (together with their formal duals) possess advanced and retarded Green operators…
Asymptotic measurement schemes for every observable of a quantum field theory
Christopher J. Fewster, Ian Jubb, Maximilian H. Ruep
In quantum measurement theory, a measurement scheme describes how an observable of a given system can be measured indirectly using a probe. The measurement scheme involves the spec…
Relative Cauchy evolution for linear homotopy AQFTs
Simen Bruinsma, Christopher J. Fewster, Alexander Schenkel
This paper develops a concept of relative Cauchy evolution for the class of homotopy algebraic quantum field theories (AQFTs) that are obtained by canonical commutation relation qu…
Algebraic Classical and Quantum Field Theory on Causal Sets
Edmund Dable-Heath, Christopher J. Fewster, Kasia Rejzner +1
The framework of perturbative algebraic quantum field theory (pAQFT) is used to construct QFT models on causal sets. We discuss various discretised wave operators, including a new…
Quantum fields and local measurements
Christopher J. Fewster, Rainer Verch
The measurement process is considered for quantum field theory on curved spacetimes. Measurements are carried out on one QFT, the "system", using another, the "probe" via a dynamic…
Probability distributions for the stress tensor in conformal field theories
Christopher J. Fewster, Stefan Hollands
The vacuum state -- or any other state of finite energy -- is not an eigenstate of any smeared (averaged) local quantum field. The outcomes (spectral values) of repeated measuremen…
Quantum Energy Inequalities in Pre-Metric Electrodynamics
Christopher J. Fewster, Christian Pfeifer, Daniel Siemssen
Pre-metric electrodynamics is a covariant framework for electromagnetism with a general constitutive law. Its lightcone structure can be more complicated than that of Maxwell theor…
An analogue of the Coleman-Mandula theorem for quantum field theory in curved spacetimes
Christopher J. Fewster
The Coleman-Mandula (CM) theorem states that the Poincaré and internal symmetries of a Minkowski spacetime quantum field theory cannot combine nontrivially in an extended symmetry…
The split property for quantum field theories in flat and curved spacetimes
Christopher J. Fewster
The split property expresses a strong form of independence of spacelike separated regions in algebraic quantum field theory. In Minkowski spacetime, it can be proved under hypothes…
Asymptotically thermal responses for smoothly switched detectors
Christopher J. Fewster, Benito A. Juárez-Aubry, Jorma Louko
Thermal phenomena in quantum field theory can be detected with the aid of particle detectors coupled to quantum fields along stationary worldlines, by testing whether the response…
Algebraic quantum field theory in curved spacetimes
Christopher J. Fewster, Rainer Verch
This article sets out the framework of algebraic quantum field theory in curved spacetimes, based on the idea of local covariance. In this framework, a quantum field theory is mode…
On the spin-statistics connection in curved spacetimes
Christopher J. Fewster
The connection between spin and statistics is examined in the context of locally covariant quantum field theory. A generalization is proposed in which locally covariant theories ar…
The split property for locally covariant quantum field theories in curved spacetime
Christopher J. Fewster
The split property expresses the way in which local regions of spacetime define subsystems of a quantum field theory. It is known to hold for general theories in Minkowski space un…
Pure quasifree states of the Dirac field from the fermionic projector
Christopher J. Fewster, Benjamin Lang
We consider the quantised free Dirac field on oriented and globally hyperbolic ultrastatic slab spacetimes with compact spatial section and demonstrate how a gauge invariant, pure…
Dynamical locality of the free Maxwell field
Christopher J. Fewster, Benjamin Lang
We consider the non-interacting source-free Maxwell field, described both in terms of the vector potential and the field strength. Starting from the classical field theory on contr…
Locally covariant quantum field theory with external sources
Christopher J. Fewster, Alexander Schenkel
We provide a detailed analysis of the classical and quantized theory of a multiplet of inhomogeneous Klein-Gordon fields, which couple to the spacetime metric and also to an extern…
Quantum Energy Inequality for the Massive Ising Model
Henning Bostelmann, Daniela Cadamuro, Christopher J. Fewster
A Quantum Energy Inequality (QEI) is derived for the massive Ising model, giving a state-independent lower bound on suitable averages of the energy density; the first QEI to be est…