Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entangled photon detection and ephemeral space-like Schr\"odinger cat
  states   A model of single photon detection, illustrated by a photon-absorbing
superfluid or superconducting microvolume, is formulated as a cascading pair of
quantum phase transitions. In the first, the microvolume transitions to the
normal state upon photon absorption, resulting in a superposition of
macrostates depending on whether the photon is absorbed or not. The second
enables subsequent "wavefunction collapse," producing a density matrix
implementing the Born probability rule. Next, EPR-type measurements on
space-like separated entangled photon pairs are considered. It is argued that
macro-entangled superposition indeed survives until such time as the component
states come into causal contact, following which the state rapidly collapses to
one or the other expected outcome. Apparent superluminal communication effects
are entirely avoided.

30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
18
The categories of this paper are: econ