Using polarized maser to detect high-frequency relic gravitational waves

TL;DR

This paper explores a method using polarized GHz maser beams to detect high-frequency relic gravitational waves, estimating sensitivity and discussing potential improvements for future detection feasibility.

Contribution

The paper develops and extends a method for detecting high-frequency relic gravitational waves using polarized maser beams and evaluates its sensitivity with current technology.

Findings

Minimal detectable GW amplitude is approximately 10^{-30}.

Current sensitivity gap is about 4-5 orders of magnitude.

Potential detector improvements could make detection feasible.

Abstract

A GHz maser beam with Gaussian-type distribution passing through a homogenous static magnetic field can be used to detect gravitational waves (GWs) with the same frequency. The presence of GWs will perturb the electromagnetic (EM) fields, giving rise to perturbed photon fluxes (PPFs). After being reflected by a fractal membrane, the perturbed photons suffer little decay and can be measured by a microwave receiver. This idea has been explored to certain extent as a method for very high frequency gravitational waves. In this paper, we examine and develop this method more extensively, and confront the possible detection with the predicted signal of relic gravitational waves (RGWs). A maser beam with high linear polarization is used to reduce the background photon fluxes (BPFs) in the detecting direction as the main noise. As a key factor of applicability of this method, we give a preliminary estimation of the sensitivity of a sample detector limited by thermal noise using currently common technology. The minimal detectable amplitude of GWs is found to be $h_{\rm{min}}\sim10^{-30}$. Comparing with the known spectrum of the RGWs in the accelerating universe for $\beta=-1.9$, there is still roughly a gap of $4\sim 5$ orders. However, possible improvements on the detector can further narrow down the gap and make it a feasible method to detect high frequency RGWs.