Abstract:
In classically chaotic systems, small differences in initial conditions are exponentially magnified over
time. However, it was observed experimentally that the (necessarily quantum) ‘‘branched flow’’ pattern of
electron flux from a quantum point contact (QPC) traveling over a random background potential in two-
dimensional electron gases remains substantially invariant to large changes in initial conditions. Since
such a potential is classically chaotic and unstable to changes in initial conditions, it was conjectured that
the origin of the observed stability is purely quantum mechanical, with no classical analog. In this Letter,
we show that the observed stability is a result of the physics of the quantum point contact and the nature of
the experiment. We show that the same stability can indeed be reproduced classically, or quantum
mechanically. In addition, we explore the stability of the branched flow with regards to changes in the
eigenmodes of the quantum point contact.
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