Fundamental quantum limits for detecting ultrahigh frequency gravitational waves

TL;DR

This paper establishes fundamental quantum limits for detecting ultrahigh-frequency gravitational waves, highlighting the potential observability of signals in the kHz-MHz range and guiding future detector development.

Contribution

It introduces a universal quantum limit framework for gravitational wave detection, providing the first fundamental bounds across different detection schemes.

Findings

Backgrounds in the kHz-MHz range are observable within quantum limits.

Higher-frequency signals above MHz are below the quantum detection threshold.

The results guide future detector designs for early universe physics exploration.

Abstract

The ultrahigh-frequency (above 10 kHz) gravitational waves (GW) window provides a unique opportunity to detect primordial GWs, free from astrophysical foregrounds that dominate lower frequencies. A stochastic GW background in this range is generically predicted from cosmological phase transitions and topological defects associated with grand unification and other ultra-high energy theories. We establish a universal quantum limit framework for various detection schemes, setting a fundamental bound on GW detectability. Our analysis reveals that backgrounds in the kHz-MHz range are in principle observable, whereas higher-frequency signals lie below the quantum limit. These results offer theoretical guidance for future detector designs and open new avenues for probing early universe physics.