Quantum transport through ballistic cavities: soft vs. hard quantum chaos

摘要

We study transport through a two-dimensional billiard attached to twoinfinite leads by numerically calculating the Landauer conductance and theWigner time delay. In the generic case of a mixed phase space we find a powerlaw distribution of resonance widths and a power law dependence of conductanceincrements apparently reflecting the classical dwell time exponent, in strikingdifference to the case of a fully chaotic phase space. Surprisingly, thesepower laws appear on energy scales {\em below} the mean level spacing, incontrast to semiclassical expectations.