Untangling colloidal caging in entangled PEG solutions

Using fluorescence microscopy, we record motion of colloids of size intermediate between correlation length of a polymer solution and size of a polymer molecule in entangled regime. The analysis of trajectory points of colloids show a transition from ``caged'' localization to diffusive randomization. The size and time spent in each individual cage is quantified using several statistical methods to give a distribution that is remarkably well-behaved and whose averages are consistent with values obtained from ensemble-average methods of trajectory analyses.