Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Matter and spin superposition in vacuum experiment (MASSIVE)   A free-falling nanodiamond containing a nitrogen vacancy centre in a spin
superposition should experience a superposition of forces in an inhomogeneous
magnetic field. We propose a practical design that brings the internal
temperature of the diamond to under 10 K. This extends the expected spin
coherence time from 2 ms to 500 ms, so the spatial superposition distance could
be increased from 0.05 nm to over 1 $\mu$m, for a 1 $\mu$m diameter diamond and
a magnetic inhomogeneity of only 10$^4$ T/m. The low temperature allows
single-shot spin readout, reducing the number of nanodiamonds that need to be
dropped by a factor of 10,000. We also propose solutions to a generic obstacle
that would prevent such macroscopic superpositions.

34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys