On the measurement predictions concerning the intrinsic relativistic spin operator

TL;DR

This paper investigates the differences between intrinsic relativistic spin and Wigner's spin, modeling measurements via electromagnetic interactions in a relativistic Stern-Gerlach setup to clarify their distinct predictions.

Contribution

It clarifies the concept of intrinsic relativistic spin and distinguishes it from Wigner's spin, proposing a measurement model using electromagnetic interactions.

Findings

Intrinsic spin differs from Wigner's spin in predictions.

Relativistic Stern-Gerlach setup models measurement of intrinsic spin.

Differences impact relativistic quantum information theory.

Abstract

Although there are several proposals of relativistic spin in the literature, the recognition of intrinsicality as a key characteristic for the definition of this concept is responsible for selecting a single tensor operator that adequately describes such a quantity. This intrinsic definition does not correspond to Wigner's spin operator, which is the definition that is widely adopted in the relativistic quantum information theory literature. Here, the differences between the predictions obtained considering the intrinsic spin and Wigner's spin are investigated. The measurements involving the intrinsic spin are modeled by means of the interaction with an electromagnetic field in a relativistic Stern-Gerlach setup.