(Sub-)proton-scale vibration measurements for future terrestrial and lunar gravitational-wave detectors

The most critical parts of the Einstein Telescope, a future terrestrial GWD, will operate at cryogenic temperatures to reduce thermal noise. We could make our current interferometric sensing and coil–magnet actuation cryo-compatible, but superconducting solutions thrive—rather than merely survive—in the cold. Using the Meissner effect, these devices enable extremely precise actuation and sensing that can be deployed near the suspended mirrors of the ET. There, they can monitor or actively mitigate tiny, unwanted vibrations. In addition to deployment in terrestrial GWDs, an array of superconducting inertial sensors could be installed in a permanently shadowed lunar crater with stable cryogenic temperatures, forming the Lunar Gravitational-wave Antenna (LGWA). I will give an overview of custom sensors from the field and how they might be used in GWDs and in industry.