Recoil experiments determine the eigenmodes of viscoelastic fluids

We experimentally investigate the recoil dynamics of a colloidal probe particle after shearing it with constant velocity through viscoelastic fluid. The displays two distinct timescales which are in excellent agreement microscopic model built on being linked to bath particles by harmonic springs. This yields analytical expressions reproduce all experimental protocols, including additional waiting periods before release. Notably, sets appear, corresponding reciprocal and nonreciprocal eigenmodes model.