Related papers: Impossible measurements require impossible apparatus

Impossible measurements require impossible apparatus

URL: http://arxiv.org/abs/2003.04660v4
Date: Mon, 26 Apr 2021 11:57:35 GMT
Title: Impossible measurements require impossible apparatus
Authors: Henning Bostelmann, Christopher J. Fewster, Maximilian H. Ruep
Abstract summary: Generalisations of quantum measurement rules can allow for superluminal signalling ('impossible measurements') We analyse this issue in a recently proposed framework in which local measurements are described physically by coupling the system to a probe. We show that the state-update rule in this setting is consistent with causality provided that the coupling between the system and probe is local.
Score: 0.0
License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Abstract: A well-recognised open conceptual problem in relativistic quantum field theory concerns the relation between measurement and causality. Naive generalisations of quantum measurement rules can allow for superluminal signalling ('impossible measurements'). This raises the problem of delineating physically allowed quantum measurements and operations. We analyse this issue in a recently proposed framework in which local measurements (in possibly curved spacetime) are described physically by coupling the system to a probe. We show that the state-update rule in this setting is consistent with causality provided that the coupling between the system and probe is local. Thus, by establishing a well-defined framework for successive measurements, we also provide a class of physically allowed operations. Conversely, impossible measurements can only be performed using impossible (non-local) apparatus.

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