Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum operations with indefinite time direction   The fundamental dynamics of quantum particles is neutral with respect to the
arrow of time. And yet, our experiments are not: we observe quantum systems
evolving from the past to the future, but not the other way round. A
fundamental question is whether it is in principle possible to conceive
operations that probe quantum processes in the backward direction, from the
future to the past, or in more general combinations of the forward and the
backward direction. To answer this question, we characterize the largest set of
bidirectional quantum processes, and we show that quantum theory is compatible
with the existence of operations that interact with these processes in an
indefinite time direction. As an explicit example, we construct an operation
that adds quantum control to the time direction of an unknown dynamics. This
operation, called the quantum time flip, exhibits an information-theoretic
advantage over all possible operations with definite time direction, even
including operations with indefinite causal order. It can realised
probabilistically using quantum teleportation, and can be reproduced
experimentally with photonic systems, shedding light on exotic scenarios in
which the arrow of time is subject to quantum indefiniteness.

28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat