7 papers
A groupoidal approach to quantum reference frames
Samuel Fedida, Alberto Ibort, Arnau Mas-Dorca
We develop the kinematical and operator-algebraic foundations of a groupoid-based relational quantum field theory (RQFT) on curved spacetimes. Indeed, the usual group-based quantum…
Foundations of Relational Quantum Field Theory I: Scalars
Samuel Fedida, Jan GÅowacki
We develop foundations for a relational approach to quantum field theory (RQFT) based on the operational quantum reference frames (QRFs) framework considered in a relativistic sett…
The thermodynamics of readout devices and semiclassical gravity
Samuel Fedida, Adrian Kent
We analyse the common claim that nonlinear modifications of quantum theory necessarily violate the second law of thermodynamics. We focus on hypothetical extensions of quantum theo…
Einstein causality of quantum measurements in the Tomonaga-Schwinger picture
Samuel Fedida
We investigate a generalisation to Lüders' rule à la Aharonov-Albert in those globally hyperbolic spacetimes which allow unitarily equivalent Hilbert spaces to be defined along Ca…
No-go theorems for pointwise-defined spinorial quantum fields
Samuel Fedida
We extend and strengthen no-go results on pointwise-defined quantum fields to cover general spinors. We show that the weak continuity of quantum fields rules out equal-time canonic…
Knot invariants and indefinite causal order
Samuel Fedida, Anne-Catherine de la Hamette, Viktoria Kabel +1
We explore indefinite causal order between events in the context of quasiclassical spacetimes in superposition. We introduce several new quantifiers to measure the degree of indefi…