Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: From quantum to quantum via decoherence   Various physical effects resulting from decoherence are discussed in the
algebraic framework. In particular, it is shown that the environment may induce
not only classical properties like superselection rules, pointer states or even
classical behavior of the quantum system, but, what is more, it also allows the
transition from statistical description of infinite quantum systems to quantum
mechanics of systems with a finite number of degrees of freedom. It is shown
that such transition holds for the quantum spin system in the thermodynamic
limit interacting with the phonon field.

34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol