Finite-frequency-dependent noise of a quantum dot in a magnetic field

Abstract

We present a detailed study for the finite- frequency current noise of a Kondo quantum dot in the presence of a magnetic field by using a recently developed real- time functional renormalization group approach [C. P. Moca, P. Simon, C. H. Chung, and G. Zarand, Phys. Rev. B 83, 201303(R) (2011)]. The scaling equations are modified in an external magnetic field; the couplings and nonlocal current vertices become strongly anisotropic, and develop new singularities. Consequently, in addition to the natural emission threshold frequency, (sis) omega = | eV |, a corresponding singular behavior is found to emerge in the noise spectrum at frequencies (sis)omega approximate to | eV +/- B|. The predicted singularities are measurable with present- day experimental techniques.