Energy shift due to anisotropic black body radiation

TL;DR

This paper derives formulas and performs calculations to understand how anisotropic black-body radiation affects atomic energy levels, which is crucial for high-precision experiments like atomic clocks and fundamental physics tests.

Contribution

The paper introduces a new formula for the anisotropic BBR shift and provides numerical results for Ca$^+$ and Yb$^+$ ions relevant to precision measurements.

Findings

Anisotropic BBR shift depends on tensor polarizability and angular momentum projection.

Numerical estimates show the magnitude of the effect for specific ions.

Anisotropic BBR shift can be a significant systematic in precision experiments.

Abstract

In many applications a source of the black-body radiation (BBR) can be highly anisotropic. This leads to the BBR shift that depends on tensor polarizability and on the projection of the total angular momentum of ions and atoms in a trap. We derived formula for the anisotropic BBR shift and performed numerical calculations of this effect for Ca$^+$ and Yb$^+$ transitions of experimental interest. These ions used for a design of high-precision atomic clocks, fundamental physics tests such as search for the Lorentz invariance violation and space-time variation of the fundamental constants, and quantum information. Anisotropic BBR shift may be one of the major systematic effect in these experiments.