Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cooling the Motion of Diamond Nanocrystals in a Magneto-Gravitational
  Trap in High Vacuum   Levitated diamond nanocrystals with nitrogen-vacancy (NV) centres in high
vacuum have been proposed as a unique system for experiments in fundamental
quantum mechanics, including the generation of large quantum superposition
states and tests of quantum gravity. This system promises extreme isolation
from its environment while providing quantum control and sensing through the NV
centre spin. While optical trapping has been the most explored method of
levitation, recent results indicate that excessive optical heating of the
nanodiamonds under vacuum may make the method impractical with currently
available materials. Here, we study an alternative magneto-gravitational trap
for diamagnetic particles, such as diamond nanocrystals, with stable levitation
from atmospheric pressure to high vacuum. Magnetic field gradients from
permanent magnets confine the particle in two dimensions, while confinement in
the third dimension is gravitational. We demonstrate that feedback cooling of
the centre-of-mass motion of a trapped nanodiamond cluster results in cooling
of one degree of freedom to less than 1 K.

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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: cs
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th