| We construct a real time current-conserving functional renormalization group (RG) scheme on the Keldysh contour to study frequency-dependent transport and noise through a quantum dot in the local moment regime. We find that the current vertex develops a non-trivial non-local structure in time, governed by a new set of RG equations. Solving these RG equations, we compute the complete frequency and temperature-dependence of the noise spectrum. For voltages large compared to the Kondo temperature, eV ≫ kBTK, two sharp anti-resonances are found in the noise spectrum at frequencies ℏω = ± eV, and correspondingly, two peaks in the ac conductance. These noise-structures can thus be interpreted as being a consequence of the splitting of the non-equilibrium Kondo resonance. |
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