Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic field imaging with NV ensembles   We demonstrate a method of imaging spatially varying magnetic fields using a
thin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip.
Fluorescence emitted by the two-dimensional NV ensemble is detected by a CCD
array, from which a vector magnetic field pattern is reconstructed. As a
demonstration, AC current is passed through wires placed on the diamond chip
surface, and the resulting AC magnetic field patterns are imaged using an
echo-based technique with sub-micron resolution over a 140 \mu m x 140 \mu m
field of view, giving single-pixel sensitivity ~100 nT/\sqrt{Hz}. We discuss
ongoing efforts to further improve sensitivity and potential bioimaging
applications such as real-time imaging of activity in functional, cultured
networks of neurons.

1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn