Fedorov, S. A.Beccari, A.Engelsen, N. J.Kippenberg, T. J.2020-03-122020-03-122020-03-122020-01-1610.1103/PhysRevLett.124.025502https://infoscience.epfl.ch/handle/20.500.14299/167202WOS:000515350300008Self-similar structures occur naturally and have been employed to engineer exotic physical properties. We show that acoustic modes of a fractal-like system of tensioned strings can display increased mechanical quality factors due to the enhancement of dissipation dilution. We describe a realistic resonator design in which the quality factor of the fundamental mode is enhanced by as much as 2 orders of magnitude compared to a simple string with the same size and tension. Our findings can open new avenues in force sensing, cavity quantum optomechanics, and experiments with suspended test masses.Physics, MultidisciplinaryPhysicstext::journal::journal article::research article