Eigenstate Selection in Open Quantum Dot Systems: On the True Nature of Level Broadening

We show that transport in open quantum dots can be mediated by single eigenstates, even when the leads allow several propagating modes. The broadening of these states, generally localized in the interior, can be virtually independent of lead width. As such, the Thouless argument, invoked to suggest that all states should be unresolvable under these conditions, can in fact fail. Thus, any transport theory based on such assumptions (in particular, random matrix theory) must be called into question, as the fluctuations produced by these states can in fact dominate the conductance. These trapped states also produce interesting and potentially useful effects in coupled dot systems as well.