Probing Virtual Axion-Like Particles by Precision Phase Measurements

TL;DR

This paper proposes a novel experiment to detect virtual axion-like particles through precision phase measurements of polarized light in a cavity, potentially covering unexplored axion mass ranges with enhanced sensitivity.

Contribution

It introduces a new cavity-based method leveraging birefringence effects and squeezed light to detect virtual ALPs, extending the search to previously untested axion mass ranges.

Findings

Enhanced phase difference signal with squeezed light source.

Ability to exclude certain axion mass ranges with small coupling.

Potential to reach sensitivity to the QCD axion.

Abstract

We propose an experiment for detecting Axion-Like Particles (ALPs) based on the axion-photon interaction in the presence of a non-uniform magnetic field. The impact of virtual ALPs on the polarization of the photons inside a cavity is studied and a detection scheme is proposed. We find that the cavity normal modes are dispersed differently owing to their coupling to the ALPs in the presence of a background magnetic field. This birefringence, in turn, can be observed as a phase difference between the cavity polarization modes. The signal is considerably enhanced for a squeezed light source. We argue that the amplified signal allows for exclusion of a range of axion mass $6\times10^{-4}\text{eV}\lesssim m_{a}\lesssim 6\times10^{-3}\text{eV}$ even at very small axion-photon coupling constant with the potential to reach sensitivity to the QCD axion. Our scheme allows for the exclusion of a range of axion masses that has not yet been covered by other experimental techniques.