Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Controlling the Momentum Current of an Off-resonant Ratchet   We experimentally investigate the phenomenon of a quantum ratchet created by
exposing a Bose-Einstein Condensate to short pulses of a potential which is
periodic in both space and time. Such a ratchet is manifested by a directed
current of particles, even though there is an absence of a net bias force. We
confirm a recent theoretical prediction [M. Sadgrove and S. Wimberger, New J.
Phys. \textbf{11}, 083027 (2009)] that the current direction can be controlled
by experimental parameters which leave the underlying symmetries of the system
unchanged. We demonstrate that this behavior can be understood using a single
variable containing many of the experimental parameters and thus the ratchet
current is describable using a single universal scaling law.

29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci