Coherent control of the optical emission in a single organic quantum wire.

We report on the first coherent control experiments on a purely electronic exciton state in an extended quasi-perfect organic quantum wire, a polydiacetylene chain isolated in the crystalline matrix of its own monomer. The time-integrated luminescence of a single wire is measured as the relative phase between two exciting sub-picosecond laser pulses is varied. From visibility functions the exciton dephasing time is extracted and its temperature dependence studied.