IntroductionSlow dynamics and aging phenomena are characteristics shared by many disordered, metastable solids. As a system is quenched into a jammed state1the constituent of the system becomes kinetically trapped, precluding further exploration of phase space. Because of the non-equilibrium nature of this state, however, most systems tend to evolve after the quench, where this evolution sensitively depends on the quench depth and on the history of the sample. Although there has been considerable theoretical effort devoted to understanding the essential physics of aging in spin and structural glasses,2–5as well as in soft glassy materials,6,7the rather general phenomena of slow dynamics in jammed systems is still poorly understood. Experiments exploring the detailed dynamics of the constituent of a system are sparse;8–12however, they are essential to gain insight in the origin of slow relaxation processes.