Electromagnetic shielding in quantum metrology

TL;DR

This paper investigates how electromagnetic vacuum fluctuations affect quantum Fisher information in atomic systems, revealing that boundaries can enhance or shield information, impacting quantum metrology precision.

Contribution

It demonstrates that boundaries can modify electromagnetic vacuum effects, allowing for potential enhancement or shielding of quantum Fisher information in atomic systems.

Findings

Vacuum fluctuations decrease quantum Fisher information without boundaries.

Boundaries can enhance or shield quantum Fisher information.

Position and atomic polarization influence information dynamics.

Abstract

The dynamics of the quantum Fisher information of the parameters of the initial atomic state and atomic transition frequency is studied, in the framework of open quantum systems, for a static polarizable two-level atom coupled in the multipolar scheme to a bath of fluctuating vacuum electromagnetic fields without and with the presence of a reflecting boundary. Our results show that in the case without a boundary, the electromagnetic vacuum fluctuations always cause the quantum Fisher information of the initial parameters and thus the precision limit of parameter estimation to decrease. Remarkably, however, with the presence of a boundary, the quantum Fisher information becomes position and atomic polarization dependent, and as a result, it may be enhanced as compared to that in the case without a boundary and may even be shielded from the influence of the vacuum fluctuations in certain circumstances as if it were a closed system.