Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phase estimation of phase shifts in two arms for an SU(1,1)
  interferometer with coherent and squeezed vacuum states   We theoretically present the quantum Cram\'{e}r-Rao bounds (QCRB) of an
SU(1,1) interferometer for Gaussian states input with and without the internal
photonic losses. The phase shifts in the single arm and in the double arms are
studied and the corresponding analytical expressions of quantum Fisher
information with Gaussian input states are presented. Different from the
traditional Mach-Zehnder interferometer, the QCRB of single arm case is
slightly higher or lower than that of double arms case depending on the input
states. With a fixed mean photon number and for pure Gaussian state input, the
optimal sensitivity is achieved with a squeezed vacuum input in one mode and
the vacuum input in the other. We compare the QCRB with the standard quantum
limit and Heisenberg limit. In the case of small internal losses the QCRB can
beat the standard quantum limit.

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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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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
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con