Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Open quantum systems in Heisenberg picture   In the framework of the Heisenberg picture, an alternative derivation of the
reduced density matrix of a driven dissipative quantum harmonic oscillator as
the prototype of an open quantum system is investigated. The reduced density
matrix for different initial states of the combined system is obtained from a
general formula, and different limiting cases are studied. Exact expressions
for the corresponding characteristic function in quantum thermodynamics and
Wigner quasi distribution function are found. A possible generalization based
on the Magnus expansion of the evolution operator is presented.

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The categories of this paper are: atom-ph
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org