Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement is an inevitable feature of any non-classical theory   One of the most striking features of quantum theory is the existence of
entangled states, responsible for Einstein's so called "spooky action at a
distance". These states emerge from the mathematical formalism of quantum
theory, but to date we do not have a clear idea of which physical principles
give rise to entanglement. Why does quantum theory have entangled states? Would
any theory superseding classical theory have entangled states, or is quantum
theory special? We demonstrate that without entanglement, non-classical degrees
of freedom cannot reversibly interact. We present two postulates, no-cloning /
no-broadcasting and local transitivity, either of which are sufficient to imply
the existence of entangled states in any non-classical theory with reversible
interactions. Therefore we argue that entanglement is an inevitable feature of
a non-classical universe.

5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg