Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Indefinite causal order enables perfect quantum communication with zero
  capacity channels   Quantum mechanics is compatible with scenarios where the relative order
between two events can be indefinite. Here we show that two independent
instances of a noisy process can behave as a perfect quantum communication
channel when used in a coherent superposition of two alternative orders. This
phenomenon occurs even if the original process has zero capacity to transmit
quantum information. In contrast, perfect quantum communication does not occur
when the message is sent directly from the sender to the receiver through a
superposition of alternative paths, with an independent noise process acting on
each path. The possibility of perfect quantum communication through independent
noisy channels highlights a fundamental difference between the superposition of
orders in time and the superposition of paths in space.

3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con