Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Antisymmetric PT-photonic structures with balanced positive and negative
  index materials   We propose a new class of synthetic optical materials in which the refractive
index satisfies $n(-\bx)=-n^*(\bx)$. We term such systems antisymmetric
parity-time (APT) structures. Unlike PT-symmetric systems which require
balanced gain and loss, i.e. $n(-\bx)=n^*(\bx)$, APT systems consist of
balanced positive and negative index materials. Despite the seemingly
PT-symmetric optical potential $V(\bx)\equiv n(\bx)^2\omega^2/c^2$, APT systems
are not invariant under combined PT operations due to the discontinuity of the
spatial derivative of the wavefunction. We show that APT systems can display
intriguing properties such as spontaneous phase transition of the scattering
matrix, bidirectional invisibility, and a continuous lasing spectrum.

16
The categories of this paper are: stat
19
The categories of this paper are: eess
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph