  We use a nanofluidic system to investigate the emergence of thermally driven
collective phenomena along a single polymer chain. In our approach, a single
DNA molecule is confined in a nanofluidic slit etched with arrays of embedded
nanocavities; the cavity lattice is designed so that a single chain occupies
multiple cavities. Fluorescent video-microscopy data shows that waves of excess
fluorescence propagate across the cavity-straddling molecule, corresponding to
propagating fluctuations of contour overdensity in the cavities. The waves are
quantified by examining the correlation in intensity fluctuations between
neighbouring cavities. Correlations grow from an anti-correlated minimum to a
correlated maximum before decaying, corresponding to a transfer of contour
between neighbouring cavities at a fixed transfer time-scale. The observed
dynamics can be modelled using Langevin dynamics simulations and a minimal
lattice model of coupled diffusion. This study shows how confinement-based
sculpting of the polymer equilibrium configuration, by renormalizing the
physical system into a series of discrete cavity states, can lead to new types
of dynamic collective phenomena.
