Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of Spin-Exchange Collisions on the Fluctuation Spectra of Hot
  Alkali Vapors   High-density alkali vapors in the spin-exchange-relaxation free (SERF) regime
are used in the highest-sensitivity optically-pumped magnetometers, atomic
gyroscopes, and searches for physics beyond the standard model, and have been
used to produce record numbers of entangled particles. Their power derives from
a counter-intuitive effect (the SERF effect) in which spin-exchange collisions
-- a decoherence mechanism at low density -- act to preserve coherence at high
density. Here we present a first-principles analysis of the noise spectra of
alkali vapors in and out of the SERF regime, and predict additional
non-intuitive features, with potential to further improve the sensitivity of
SERF media, and which must be taken into account in their use in quantum
optical applications. Studying the process of spin-noise spectroscopy (SNS), we
derive analytic formulae for the observable noise spectra, and for the
correlation functions among different hyperfine components, which give
additional insight into the spin dynamics. The analytic results indicate a
variety of distortions of the spin-noise spectrum relative to simpler models,
including a broad spectral background that mimics optical shot noise,
interference of noise contributions from the two ground state hyperfine levels,
noise reduction at the spin-precession frequency, and "hiding" of spin-noise
power that can introduce a systematic error in noise-based calibrations, e.g.
for spin-squeezing experiments.

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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph