Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: All-optical high-resolution magnetic resonance using a nitrogen-vacancy
  spin in diamond   We propose an all-optical scheme to prolong the quantum coherence of a
negatively charged nitrogen-vacancy (NV) center in diamond. Optical control of
the NV spin suppresses energy fluctuations of the $^{3}\text{A}_{2}$ ground
states and forms an energy gap protected subspace. By optical control, the
spectral linewidth of magnetic resonance is much narrower and the measurement
of the frequencies of magnetic field sources has higher resolution. The optical
control also improves the sensitivity of the magnetic field detection and can
provide measurement of the directions of signal sources.

31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
3
The categories of this paper are: physics