The Local Lorentz Symmetry Violation and Einstein Equivalence Principle

TL;DR

This paper investigates local Lorentz symmetry violation within a quantum framework, demonstrating that such violations also imply a violation of the Einstein equivalence principle, with experimental bounds indicating very small effects.

Contribution

It connects Lorentz violation to quantum violations of the Einstein equivalence principle and estimates the violation parameter using atomic experiments.

Findings

Violation parameter is very small, consistent with theoretical expectations.

LV effect is both local and classically violates EEP.

Experimental bounds constrain the magnitude of the violation.

Abstract

Lorentz symmetry violation (LV) was recently proposed to be testable with a new method, in which the effect of the violation is described as a certain local interaction [R. Shaniv, et al, PRL 120, 103202 (2018)]. We revisit this LV effect in the paper and show that it is not only local, but it also represents a classical violation according to the recent quantum formulation of the Einstein equivalence principle (EEP). Based on a harmonically trapped spin-1/2 atomic system, we apply the results of table-top experiments testing LV effect to estimate the corresponding violation parameter in the quantum formulation of EEP. We find that the violation parameter is indeed very small, as expected by the earlier theoretical estimation.