Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of quincunx-shaped and dipole-like flatband states in
  photonic rhombic lattices without band-touching   We demonstrate experimentally the existence of compact localized states
(CLSs) in a quasi-one-dimensional photonic rhombic lattice in presence of two
distinct refractive-index gradients (i.e., a driven lattice ribbon) acting as
external direct current (dc) electric fields. Such a lattice is composed of an
array of periodically arranged evanescently coupled waveguides, which hosts a
perfect flatband that touches both remaining dispersive bands when it is not
driven. The external driving is realized by modulating the relative writing
beam intensity of adjacent waveguides. We find that a y-gradient set
perpendicularly to the ribbon preserves the flatband while removing the
band-touching. The undriven CLS - which occupies two lattices sites over one
unit cell - turns into a quincunx-shaped CLS spanned over two unit cells.
Instead, an x-gradient acting parallel to the ribbon yields a Stark ladder of
CLS whose spatial profile is unchanged with respect to the undriven case. We
notably find that their superposition leads to Bloch-like oscillations in
momentum space.

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The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th