2014/12/31 by Akira Oguri, Rui Sakano
Mathematics · Physics and Astronomy · #Anderson impurity model #Context (archaeology) #Fock space #Hamiltonian (control theory) #Impurity #Mathematical physics #Mathematics #Non-equilibrium thermodynamics #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum many-body systems #Quantum mechanics #Thermal equilibrium #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.91.115429
published as Phys. Rev. B 91, 115429 (2015) · 16 pages, 6 figures, typos have been corrected and DOI has been provided
openalex publication_date 2015/03/24 · arxiv created 2015/03/25 · arxiv updated 2015/03/26 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the nonequilibrium Keldysh Green's function for an N-orbital Anderson model at high bias voltages, extending a previous work which for the case only with the spin degrees of freedom N=2 to arbitrary N. Our approach uses an effective non-Hermitian Hamiltonian that is defined with respect to a Liouville-Fock space in the context of a thermal field theory. The result correctly captures the relaxation processes at high energies, and is asymptotically exact not only in the high bias limit, but also in the high-temperature limit at thermal equilibrium. We also present an explicit continued-fraction representation of the Green's function. It clearly shows that the imaginary part is recursively determined by the decay rate of intermediate states with at most N\ensuremath-1 particle-hole-pair excitations. These high bias properties follow from the conservations of a generalized charge and current in the Liouville-Fock space. We also examine temperature dependence of the spectral function in equilibrium, comparing the exact results with the numerical finite-T and analytical T\ensuremath→\ensuremath∞ results of the noncrossing approximation.