Fractional Shot Noise in the Kondo Regime

Low temperature transport through a quantum dot in the Kondo regime proceeds by a universal combination of elastic and inelastic processes, as dictated by the low-energy Fermi-liquid fixed point. We show that as a result of inelastic processes, the charge detected by a shot-noise experiment is enhanced relative to the noninteracting situation to a universal fractional value, $e^{\ast }=5\mathrm{/}3e$. Thus, shot noise reveals that the Kondo effect involves many-body features even at low energies, despite its Fermi-liquid nature. We discuss the influence of symmetry breaking perturbations.