Semiclassical wavefunctions in chaotic scattering systems

We have computed quantum wavefunctions in the high-energy (semiclassical) regime in a system-the stadium billiard with leads allowing particles to enter and escape-exemplifying chaotic scattering. The results exhibit a structure associated with classical paths that is dramatically more pronounced than the scars due to periodic orbits seen in bound systems. Moreover, this structure is seen at all energies. Our results differ significantly from those previously conjectured on the basis of computations in the low-energy regime. The dominant role played by short classical paths is explained by a semiclassical theory based on the analytic structure of the Green function. This is verified by a direct semiclassical computation of wavefunctions using classical scattering trajectories.