  We report on single-particle dynamics of strongly interacting filamentous fd
virus particles in the liquid-crystalline columnar state in aqueous solution.
From fluorescence microscopy we find that rare, discrete events take place, in
which individual particles engage in sudden, jump-like motion along the main
rod axis. The jump length distribution is bimodal and centered at half and full
particle lengths. Our Brownian dynamics simulations of hard semi-flexible
particles mimic our experiments, and indicate that full-length jumps must be
due to collective dynamics in which particles move in string-like fashion in
and between neighboring columns, while half jumps arise as a result of
particles moving into defects. We find that the finite domain structure of the
columnar phase strongly influences the observed dynamics.
