Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structural Phase Transitions of Optical Patterns in Atomic Gases with
  Microwave Controlled Rydberg Interactions   Spontaneous symmetry breaking and formation of self-organized structures in
nonlinear systems are intriguing and important phenomena in nature. Advancing
such research to new nonlinear optical regimes is of much interest for both
fundamental physics and practical applications. Here we propose a scheme to
realize optical pattern formation in a cold Rydberg atomic gas via
electromagnetically induced transparency. We show that, by coupling two Rydberg
states with a microwave field (microwave dressing), the nonlocal Kerr
nonlinearity of the Rydberg gas can be enhanced significantly and may be tuned
actively. Based on such nonlocal Kerr nonlinearity, we demonstrate that a
plane-wave state of probe laser field can undergo a modulation instability (MI)
and hence spontaneous symmetry breaking, which may result in the emergence of
various self-organized optical patterns. Especially, we find that a hexagonal
lattice pattern (which is the only optical pattern when the microwave dressing
is absent) may develop into several types of square lattice ones when the
microwave dressing is applied; moreover, as a outcome of the MI the formation
of nonlocal optical solitons is also possible in the system. Different from
earlier studies, the optical patterns and nonlocal optical solitons found here
can be flexibly manipulated by adjusting the effective probe-field intensity,
nonlocality degree of the Kerr nonlinearity, and the strength of the microwave
field. Our work opens a route for versatile controls of self-organizations and
structural phase transitions of laser light, which may have potential
applications in optical information processing and transmission.

30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs