2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129742We review our recent measurements of the complex AC conductivity of thin InO_x films studied as a function of magnetic field through the nominal 2D superconductor-insulator transition. These measurements - the first of their type to probe nonzero frequency - reveals a significant finite frequency superfluid stiffness well into the insulating regime. Unlike conventional fluctuation superconductivity in which thermal fluctuations give a superconducting response in regions of parameter space that don't exhibit long range order, these fluctuations are temperature independent as T --> 0 and are exhibited in samples where the resistance is large (greater than 10^6 Ohms/Square) and strongly diverging. We interpret this as the direct observation of quantum superconducting fluctuations around an insulating ground state. This system serves as a prototype for other insulating states of matter that derive from superconductors.Submitted to the proceedings of SCES07SuperconductivityDisordered Systems and Neural Networkstext