Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-time quantum transport and quantum diffusion   Based on the nonequilibrium Green's function technique, a unified theory is
developed that covers quantum transport and quantum diffusion in bulk
semiconductors on the same footing. This approach, which is applicable to
transport via extended and localized states, extends previous
semi-phenomenological studies and puts them on a firm microscopic basis. The
approach is sufficiently general and applies not only to well-studied quantum
transport problems, but also to models, in which the Hamiltonian does not
commute with the dipole operator. It is shown that, even for the unified
treatment of quantum transport and quantum diffusion in homogeneous systems,
all quasi-momenta of the carrier distribution function are present and fulfill
their specific function. Particular emphasis is put on the double-time nature
of quantum kinetics. To demonstrate the existence of robust macroscopic
transport effects that have a true double-time character, a phononless
steady-state current is identified that appears only beyond the generalized
Kadanoff-Baym ansatz.

11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas