Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: State Readout of a Trapped Ion Qubit Using a Trap-Integrated
  Superconducting Photon Detector   We report high-fidelity state readout of a trapped ion qubit using a
trap-integrated photon detector. We determine the hyperfine qubit state of a
single $^9$Be$^+$ ion held in a surface-electrode rf ion trap by counting
state-dependent ion fluorescence photons with a superconducting nanowire
single-photon detector (SNSPD) fabricated into the trap structure. The average
readout fidelity is 0.9991(1), with a mean readout duration of 46 $\mu$s, and
is limited by the polarization impurity of the readout laser beam and by
off-resonant optical pumping. Because there are no intervening optical elements
between the ion and the detector, we can use the ion fluorescence as a
self-calibrated photon source to determine the detector quantum efficiency and
its dependence on photon incidence angle and polarization.

31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph