Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Second-Scale Coherence Measured at the Quantum Projection Noise Limit
  with Hundreds of Molecular Ions   Cold molecules provide an excellent platform for quantum information, cold
chemistry, and precision measurement. Certain molecules have enhanced
sensitivity to beyond Standard Model physics, such as the electron's electric
dipole moment ($e$EDM). Molecular ions are easily trappable and are therefore
particularly attractive for precision measurements where sensitivity scales
with interrogation time. Here, we demonstrate a spin precession measurement
with second-scale coherence at the quantum projection noise (QPN) limit with
hundreds of trapped molecular ions, chosen for their sensitivity to the $e$EDM
rather than their amenability to state control and readout.
Orientation-resolved resonant photodissociation allows us to simultaneously
measure two quantum states with opposite $e$EDM sensitivity, reaching the QPN
limit and fully exploiting the high count rate and long coherence.

33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom