Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 'Plasmonics' in free space: observation of giant wavevectors, vortices
  and energy backflow in superoscillatory optical fields   Evanescent light can be localized at the nanoscale by resonant absorption in
a plasmonic nanoparticle or taper or by transmission through a nanohole.
However, a conventional lens cannot focus free-space light beyond half of the
wavelength {\lambda}. Nevertheless, precisely tailored interference of multiple
waves can form a hotspot in free space of arbitrarily small size known as
superoscillation. Here, we report a new type of integrated metamaterial
interferometry that allows for the first time mapping of fields with deep
subwavelength resolution ~ {\lambda}/100. It reveals that electromagnetic field
near the superoscillatory hotspot has many features similar to those found near
resonant plasmonic nanoparticles or nanoholes: the hotspots are surrounded by
nanoscale phase singularities (~ {\lambda}/50 in size) and zones where the
phase of the wave changes more than tenfold faster than in a standing wave.
These areas with high local wavevectors are pinned to phase vortices and zones
of energy backflow (~ {\lambda}/20 in size) that contribute to tightening of
the main focal spot size beyond the Abbe-Rayleigh limit. Our observations
reveal the analogy between plasmonic nano-focusing of evanescent waves and
superoscillatory nano-focusing of free-space waves, and prove the fundamental
link between superoscillations and superfocusing offering new opportunities for
nanoscale metrology and imaging.

33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con