Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: No-faster-than-light-signaling implies linear evolutions. A
  re-derivation   There is a growing interest, both from the theoretical as well as
experimental side, to test the validity of the quantum superposition principle,
and of theories which explicitly violate it by adding nonlinear terms to the
Schr\"odinger equation. We review the original argument elaborated by Gisin
(1989 Helv. Phys. Acta 62 363), which shows that the non-superluminal-signaling
condition implies that the dynamics of the density matrix must be linear. This
places very strong constraints on the permissible modifications of the
Schr\"odinger equation, since they have to give rise, at the statistical level,
to a linear evolution for the density matrix. The derivation is done in a
heuristic way here and is appropriate for the students familiar with the
textbook quantum mechanics and the language of density matrices.

36
The categories of this paper are: cmp-lg
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
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con