Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-parameter Quantum Magnetometry with Spin States in coarsened
  measurement reference   We investigate the simultaneous estimation of the intensity and the
orientation of a magnetic field by the multi-parameter quantum Fisher
information matrix. A general expression is achieved for the simultaneous
estimation precision of the intensity and the orientation, which is better than
the independent estimation precision for the given number of spin states.
Moreover, we consider an imperfect measurement device, coarsened measurement
reference. For the case of the measurement reference rotating around the
$y-$axis randomly, the simultaneous estimation always performs better than the
independent estimation. For all other cases, the simultaneous estimation
precision will not perform better than the independent estimation when the
coarsened degree is larger than a certain value.

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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: math
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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: physics
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph