Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic spin imaging under ambient conditions with sub-cellular
  resolution   Measuring spins is the corner stone of a variety of analytical techniques
including modern magnetic resonance imaging (MRI). The full potential of spin
imaging and sensing across length scales is hindered by the achievable
signal-to-noise in inductive detection schemes. Here we show that a proximal
Nitrogen-Vacancy (NV) ensemble serves as a precision sensing array. Monitoring
its quantum relaxation enables sensing of freely diffusing and unperturbed
magnetic ions in a microfluidic device. Multiplexed CCD acquisition and an
optimized detection scheme enable direct spin noise imaging under ambient
conditions with experimental sensitivities down to 1000 statistically polarized
spins, of which only 35 ions contribute to a net magnetization, and 20 s
acquisition time. We also demonstrate imaging of spin labeled cellular
structures with spatial resolutions below 500 nm. Our study marks a major step
towards sub-{\mu}m imaging magnetometry and applications in microanalytics,
material and life sciences.

2
The categories of this paper are: math
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph