Probing For New Physics and Detecting non linear vacuum QED effects using gravitational wave interferometer antennas

TL;DR

This paper explores using gravitational wave interferometers like VIRGO to detect nonlinear QED effects and new physics, proposing a magnetic field implementation that enhances sensitivity for such measurements.

Contribution

It introduces an almost parasitic magnetic field setup along VIRGO's arms to improve detection of vacuum nonlinearities and new physics, contrasting with previous configurations.

Findings

VIRGO+ can potentially detect QED effects with strain sensitivity of 2×10⁻²³/√Hz.

Proposed magnetic field configuration achieves B²D ≥ 13000 T²m/√Hz for detection.

The approach offers a feasible method for probing vacuum nonlinearities with existing interferometers.

Abstract

Low energy non linear QED effects in vacuum have been predicted since 1936 and have been subject of research for many decades. Two main schemes have been proposed for such a 'first' detection: measurements of ellipticity acquired by a linearly polarized beam of light passing through a magnetic field and direct light-light scattering. The study of the propagation of light through an external field can also be used to probe for new physics such as the existence of axion-like particles and millicharged particles. Their existence in nature would cause the index of refraction of vacuum to be different from unity in the presence of an external field and dependent of the polarization direction of the light propagating. The major achievement of reaching the project sensitivities in gravitational wave interferometers such as LIGO an VIRGO has opened the possibility of using such instruments for the detection of QED corrections in electrodynamics and for probing new physics at very low energies. In this paper we discuss the difference between direct birefringence measurements and index of refraction measurements. We propose an almost parasitic implementation of an external magnetic field along the arms of the VIRGO interferometer and discuss the advantage of this choice in comparison to a previously proposed configuration based on shorter prototype interferometers which we believe is inadequate. Considering the design sensitivity in the strain, for the near future VIRGO+ interferometer, of $h<2\cdot10^{-23} \frac{1}{\sqrt{\rm Hz}}$ in the range 40 Hz $- 400$ Hz leads to a variable dipole magnet configuration at a frequency above 20 Hz such that $B^{2}D \ge 13000$ T$^{2}$m/$\sqrt{\rm Hz}$ for a `first' vacuum non linear QED detection.