A Broadband Room-Temperature Design for the Einstein Telescope
Abstract
The unique underground location of the Einstein Telescope (ET) is expected to substantially suppress seismic and gravity-gradient noise, providing a favorable environment for gravitational-wave detection at low frequencies compared with surface-based observatories. The baseline ET design aims to achieve broadband sensitivity through a xylophone configuration, in which separate cryogenic and room-temperature interferometers are optimised for low- and high-frequency gravitational-wave detection. However, achieving the target low-frequency sensitivity introduces substantial technical complexity caused by vertical suspension thermal noise, vibrations of the cryocooler, and detuned optical configuration. In this paper, we demonstrate an alternative, entirely room-temperature, fully resonant, single-interferometer architecture that addresses these challenges and achieves broadband sensitivity superior to that of the conventional ET xylophone configuration. Using mature fused-silica suspension technology, recent advances in optical coatings, and novel inertial isolation, we show that 4-m-long fused-silica fibres can meet the required suspension thermal-noise performance. We further demonstrate that vibrations, optical rigidity, and quantum back-action noise can be controlled through appropriate design of the interferometer, test mass suspensions, optical seismometers, and quantum states.
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BibTeX
@misc{zhang2026broadband,
title = {{A Broadband Room-Temperature Design for the Einstein Telescope}},
author = {Teng Zhang and Amit Singh Ubhi and Huan Yang and Alan V. Cumming and Mark Barton and Angus Bell and Fabio Bergamin and Giacomo Bruno and Katherine L. Dooley and Johannes Eichholz and Mariana Fazio and Aaron Goodwin-Jones and James Hough and Keiko Kokeyama and Haixing Miao and Xingrui Peng and Geraint Pratten and Stuart Reid and Sheila Rowan and Patricia Schmidt and Alberto Vecchio and Giles Hammond and Hartmut Grote and Denis Martynov},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29863},
eprint = {2610.29863},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29863},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Broadband Room-Temperature Design for the Einstein Telescope
AU - Teng Zhang
AU - Amit Singh Ubhi
AU - Huan Yang
AU - Alan V. Cumming
AU - Mark Barton
AU - Angus Bell
AU - Fabio Bergamin
AU - Giacomo Bruno
AU - Katherine L. Dooley
AU - Johannes Eichholz
AU - Mariana Fazio
AU - Aaron Goodwin-Jones
AU - James Hough
AU - Keiko Kokeyama
AU - Haixing Miao
AU - Xingrui Peng
AU - Geraint Pratten
AU - Stuart Reid
AU - Sheila Rowan
AU - Patricia Schmidt
AU - Alberto Vecchio
AU - Giles Hammond
AU - Hartmut Grote
AU - Denis Martynov
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29863
UR - https://arxiv.org/abs/2610.29863
AB - The unique underground location of the Einstein Telescope (ET) is expected to substantially suppress seismic and gravity-gradient noise, providing a favorable environment for gravitational-wave detection at low frequencies compared with surface-based observatories. The baseline ET design aims to achieve broadband sensitivity through a xylophone configuration, in which separate cryogenic and room-temperature interferometers are optimised for low- and high-frequency gravitational-wave detection. However, achieving the target low-frequency sensitivity introduces substantial technical complexity caused by vertical suspension thermal noise, vibrations of the cryocooler, and detuned optical configuration. In this paper, we demonstrate an alternative, entirely room-temperature, fully resonant, single-interferometer architecture that addresses these challenges and achieves broadband sensitivity superior to that of the conventional ET xylophone configuration. Using mature fused-silica suspension technology, recent advances in optical coatings, and novel inertial isolation, we show that 4-m-long fused-silica fibres can meet the required suspension thermal-noise performance. We further demonstrate that vibrations, optical rigidity, and quantum back-action noise can be controlled through appropriate design of the interferometer, test mass suspensions, optical seismometers, and quantum states.
ER -