Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rocking ratchets in 2D Josephson networks: collective effects and
  current reversal   A detailed numerical study on the directed motion of ac-driven vortices and
antivortices in 2D Josephson junction arrays (JJA) with an asymmetric periodic
pinning potential is reported. Dc-voltage rectification shows a strong
dependence on vortex density as well as an inversion of the vortex flow
direction with ac amplitude for a wide range of vortex density around $f$=1/2
($f$=$Ha^2 / \Phi_0$), in good agreement with recent experiments by Shal\'om
and Pastoriza [Phys. Rev. Lett. {\bf 94}, 177001 (2005)]. The study of vortex
structures, spatial and temporal correlations, and vortex-antivortex pairs
formation gives insight into a purely collective mechanism behind the current
reversal effect.

5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
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The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg