Self-Similar Magnetoconductance Fluctuations Induced by Self-Similar Periodic Orbits

概要

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Using the semiclassical Kubo formula for conductivity, we give a periodic-orbit picture for the recently observed fractal magnetoconductance fluctuations in submicron-scale phase coherent ballistic billiards. The self-similar conductance fluctuations are shown to be caused by the self-similar unstable periodic orbits which are generated through a sequence of isochronous pitchfork bifurcations of straight-line librating orbits oscillating towards harmonic saddles. The saddles are naturally created right at the point of contact with the leads or at certain places in the cavity as a consequence of the softwall confinement. Therefore, our mechanism is able to explain all the self-similar magnetoconductance fluctuations in general softwall billiards. In contrast to the existing theory which claims that a classical mixed phase space is necessary, we argue that, even in the fully chaotic phase space, the self-similar magnetoconductance fluctuations should be observed as long as the self-similar unstable periodic orbits are preserved.
社団法人日本物理学会の論文
2002-09-15