PERIODIC CONDUCTANCE FLUCTUATIONS AND LEAD-INDUCED SCARRING IN OPEN QUANTUM DOTS

We consider the nature of ballistic electron transport in open mesosco pic cavities, coupled to external reservoirs by means of few-mode quan tum point contacts. The devices vary in size over a wide range and the discrete nature of their electronic energy spectrum is expected to st rongly influence the resulting electrical behaviour. Electron interfer ence is also an important process in these devices and is investigated through studies of their low-temperature magneto-resistance. This is found to be characterized by regular fluctuations, which numerical sim ulations reveal to be associated with periodically recurring wavefunct ion scarring. Further analysis shows that the scarring is established by the collimating action of the injecting point contact, the quantum mechanical nature of which ensures that just a few cavity modes are ex cited to participate in transport. We therefore conclude that chaotic scattering is suppressed in mesoscopic cavities once their discrete qu antum mechanical nature becomes resolved. Transport then instead occur s via a small number of regular orbits, which are stabilized by the ro le of the quantum point contact leads and the discrete quantization wi thin the cavity itself. These long orbits give rise to well defined wa vefunction scarring with measurable magneto-transport results.