  We use Time Resolved Correlation (TRC), a recently introduced light
scattering method, to study the dynamics of a variety of jammed, or glassy,
soft materials. The output of a TRC experiment is cI(t,tau), the time series of
the degree of correlation between the speckle patterns generated by the light
scattered at time t and t+tau. We characterize the fluctuations of cI by
calculating their Probability Density Function, their variance as a function of
the lag tau, and their time autocorrelation function. The comparison between
these quantities for a Brownian sample and for jammed materials indicate
unambiguously that the slow dynamics measured in soft glasses is temporally
heterogeneous. The analogies with recent experimental, numerical and
theoretical work on temporal heterogeneity in the glassy dynamics are briefly
discussed.
