Demonstration that Differential Length Changes of Optical Cavities are a Sensitive Probe for Ultralight Dark Matter

TL;DR

This paper demonstrates that measuring differential length oscillations in optical cavities is a highly sensitive method for detecting scalar ultralight dark matter, establishing new bounds and potential for broader mass range detection.

Contribution

It introduces a novel optical cavity measurement technique for ultralight dark matter detection, setting new lower bounds and highlighting increased sensitivity over a wide mass range.

Findings

Set lower bounds for ULDM models that are 10-100 times more restrictive.

Demonstrated sensitivity across a decade of ULDM mass and frequency.

Indicated potential for significantly higher sensitivity with improved methods.

Abstract

Measurements of differential length oscillations of Fabry-Perot cavities provide a sensitive and promising approach to searching for scalar ultralight dark matter (ULDM). The initial demonstration sets direct lower bounds that are one to two orders of magnitude lower for two model ULDM distributions -- a standard galactic halo and a relaxion star bound to Earth -- ranging over a decade of ULDM mass and Compton frequency. The demonstration suggests how a much higher sensitivity to a much larger ULDM mass range can be obtained.