Searching for photon-sector Lorentz violation using gravitational-wave detectors

TL;DR

This paper explores how gravitational-wave detectors can be used to detect tiny violations of Lorentz symmetry in the photon sector, leveraging their sensitivity to changes in light’s refractive index at very low frequencies.

Contribution

It demonstrates the potential of existing gravitational-wave interferometers to set new, more stringent constraints on Lorentz violation in the photon sector using preliminary LIGO data.

Findings

LIGO data constrains Lorentz violation coefficients four orders of magnitude better than previous limits.

Interferometers are highly sensitive to refractive index changes at microhertz frequencies.

Existing gravitational-wave detectors can be repurposed for fundamental tests of Lorentz symmetry.

Abstract

We study the prospects for using interferometers in gravitational-wave detectors as tools to search for photon-sector violations of Lorentz symmetry. Existing interferometers are shown to be exquisitely sensitive to tiny changes in the effective refractive index of light occurring at frequencies around and below the microhertz range, including at the harmonics of the frequencies of the Earth's sidereal rotation and annual revolution relevant for tests of Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on coefficients for Lorentz violation in the photon sector exceeding current limits by about four orders of magnitude.