Quantum suppression of the Rayleigh instability in nanowires

A linear stability analysis of metallic nanowires is performed in the free- electron model using quantum chaos techniques. It is found that the classic al instability of a long wire under surface tension can be completely suppr essed by electronic shell effects, leading to stable cylindrical configurat ions whose electrical conductance is a magic number 1, 3, 5, 6,... times th e quantum of conductance. Our results are quantitatively consistent with re cent experiments with alkali metal nanowires. AMS classification scheme num bers: 76E17, 81Q50, 82D35.