Current noise and Keldysh vertex function of an Anderson impurity in the Fermi-liquid regime

Article

关键词: RENORMALIZATION-GROUP APPROACH;    DILUTE MAGNETIC-ALLOYS;    PERTURBATION EXPANSION;    STATIC PROPERTIES;    TRANSPORT;    MODEL;   

DOI  :  10.1103/PhysRevB.105.115409

来源: SCIE

【 摘 要 】

We present a complete microscopic Fermi-liquid description for next-to-leading order transport through an Anderson impurity under a finite bias voltage V. It is applicable to multilevel quantum dots without particlehole or time-reversal symmetry and is constructed based on the nonequilibrium Keldysh formalism, taking into account the current conservation between electrons in the impurity levels and the conduction bands. Specifically, we derive the formula for the current noise generated in the steady flow up to terms of order (eV)(3) at zero temperature T = 0. To this end, we calculate the Keldysh vertex functions Gamma(nu 1 nu 2;nu 3 nu 4)(sigma sigma';sigma'sigma) (omega, omega'; omega', omega), which depend on branches nu(1), nu(2), nu(3), and nu(4) of the time-loop contour and on spin degrees of freedom sigma and sigma', up to linear order terms with respect to eV, T, and frequencies omega and omega'. The coefficients of these linear order terms are determined by a set of the parameters, defined with respect to the equilibrium ground state: the phase shift, static susceptibilities, and nonlinear three-body susceptibilities of the impurity electrons. The low-energy expressions of the vertex components are shown to satisfy the Ward identities with the Keldysh Green's functions expanded up to terms of order omega(2), (eV)(2) , and T-2. We also find that the imaginary part of the Ward identities can be described in terms of the eV-dependent collision integrals for a single-quasiparticle excitation and that for a single quasiparticle-quasihole pair excitation. These collision integrals ensure the current conservation of the next-to-leading order Fermi-liquid transport due to the quasiparticles with a finite damping rate.

【 授权许可】

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