The Quantum-Enhanced Space-Time (QUEST) experiment consists of a pair of co-located Power Recycled Michelson Interferometers, each designed to have a broadband, shot-noise limited displacement sensitivity of 2×10−19m/Hz from 1 to 200 MHz. Here we present the first results of QUEST that set new upper limits on correlated length fluctuations from 13 to 80 MHz, constituting the first broadband constraints for a stochastic gravitational wave background at these frequencies. In a coincident observing run of 104 s the averaging of the cross-correlation spectra between the two interferometer signals resulted in a strain sensitivity of 3×10−201/Hz at 40 MHz, making QUEST the most sensitive table-top interferometric system to date.
@article{arxiv.2410.09175,
title = {Broadband limits on stochastic length fluctuations from a pair of table-top interferometers},
author = {Abhinav Patra and Lorenzo Aiello and Aldo Ejlli and William L. Griffiths and Alasdair L. James and Nikitha Kuntimaddi and Ohkyung Kwon and Eyal Schwartz and Henning Vahlbruch and Sander M. Vermeulen and Keiko Kokeyama and Katherine L. Dooley and Hartmut Grote},
journal= {arXiv preprint arXiv:2410.09175},
year = {2025}
}