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Description
Cooling down ET to cryogenic temperatures may introduce tiny, unwanted vibrations near the suspended mirrors that even the most sensitive existing sensors cannot detect. By exploiting the Meissner effect, superconducting thin-film dual-coil designs will enable sub-femtometer precision sensing and high-precision actuation with negligible heat dissipation. We present a deposition-based design methodology for thin-film coils compatible with higher operating temperatures in ET than conventional wirewound coils, which require liquid helium temperatures. Fabricated niobium nitride (NbN) coils achieved a critical temperature of 14.2 K and critical currents up to 180 mA, demonstrating persistent currents scalable up to ampere-level in thin films. COMSOL-optimized coil designs further show that these coils can exert sub-micronewton forces on a superconducting surface maintained entirely in the Meissner state. These results show the feasibility of a new generation of superconducting sensing and actuation solutions in the ET cryostat.