Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Indirect Methods to Control Population Distribution in a Large Spin
  System   We demonstrate how a large spin system ($S=7/2$) with the ground and the
first excited state separated by a seven photon transition exhibit non
equilibrium thermodynamic properties and how the population distribution may be
manipulated using coupling between energy levels. The first method involves
non-adiabatic passage through an avoided level crossing controlled with an
external DC magnetic field and the resulting Landau Zener transition. The
second method is based on external cavity pumping to a higher energy state
hybridised with another state that is two single photon transitions away from
the ground state. The results are confirmed experimentally with Gd$^{3+}$
impurity ion ensemble in a YVO$_{4}$ crystal cooled to 20 mK, which also acts
as a microwave photonic whispering gallery mode resonator. Extremely long life
times are observed due to large number of photons required for the transition
between the ground and the first excited states.

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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: stat
6
The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: eess