Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The connection between time-local and time-nonlocal perturbation
  expansions   There exist two canonical approaches to describe open quantum systems by a
time-evolution equation: the Nakajima-Zwanzig quantum master equation,
featuring a time-nonlocal memory kernel $\mathcal{K}$, and the
time-convolutionless equation with a time-local generator $\mathcal{G}$. These
key quantities have recently been shown to be connected by an exact fixed-point
relation [Phys. Rev. X 11, 021041 (2021)]. Here we show that this implies a
recursive relation between their perturbative expansions, allowing a series for
the kernel $\mathcal{K}$ to be translated directly into a corresponding series
for the more complicated generator $\mathcal{G}$. This leads to an elegant way
of computing the generator using well-developed, standard memory-kernel
techniques for strongly interacting open systems. Moreover, it allows for an
unbiased comparison of time-local and time-nonlocal approaches independent of
the particular technique chosen to calculate expansions of $\mathcal{K}$ and
$\mathcal{G}$ (Nakajima-Zwanzig projections, real-time diagrams, etc.). We
illustrate this for leading and next-to-leading order calculations of
$\mathcal{K}$ and $\mathcal{G}$ for the single impurity Anderson model using
both the bare expansion in the system-environment coupling and a more advanced
renormalized series. We compare the different expansions obtained, quantify the
legitimacy of the generated dynamics (complete positivity) and benchmark with
the exact result in the non-interacting limit.

27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn