Relativistic quantum measurement

TL;DR

This paper introduces a Lorentz invariant model for quantum measurement of a relativistic particle's spacetime localization, challenging the notion that measurement necessarily breaks Lorentz invariance.

Contribution

It presents a simple, Lorentz invariant detector model for single-particle quantum measurement, avoiding preferred frames unlike previous approaches.

Findings

The detector measures spacetime localization without breaking Lorentz invariance.

The model supports the existence of a Lorentz invariant quantum measurement concept.

It provides insights into relativistic particle localization within single-particle quantum mechanics.

Abstract

Does the measurement of a quantum system necessarily break Lorentz invariance? We present a simple model of a detector that measures the spacetime localization of a relativistic particle in a Lorentz invariant manner. The detector does not select a preferred Lorentz frame as a Newton-Wigner measurement would do. The result indicates that there exists a Lorentz invariant notion of quantum measurement and sheds light on the issue of the localization of a relativistic particle. The framework considered is that of single-particle mechanics as opposed to field theory. The result may be taken as support for the interpretation postulate of the spacetime-states formulation of single-particle quantum theory.