Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Detection of a single fundamental charge with nanoscale resolution in
  ambient conditions using the NV$^-$ center in diamond
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas