Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Delayed choice for entanglement swapping   Two observers (Alice and Bob) independently prepare two sets of singlets.
They test one particle of each singlet along an arbitrarily chosen direction
and send the other particle to a third observer, Eve. At a later time, Eve
performs joint tests on pairs of particles (one from Alice and one from Bob).
According to Eve's choice of test and to her results, Alice and Bob can sort
into subsets the samples that they have already tested, and they can verify
that each subset behaves as if it consisted of entangled pairs of distant
particles, that have never communicated in the past, even indirectly via other
particles.

37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
18
The categories of this paper are: econ