Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimal waveform estimation for classical and quantum systems via
  time-symmetric smoothing. II. Applications to atomic magnetometry and Hardy's
  paradox   The quantum smoothing theory [Tsang, Phys. Rev. Lett. 102, 250403 (2009);
Phys. Rev. A, in press (e-print arXiv:0906.4133)] is extended to account for
discrete jumps in the classical random process to be estimated, discrete
variables in the quantum system, such as spin, angular momentum, and photon
number, and Poissonian measurements, such as photon counting. The extended
theory is used to model atomic magnetometers and study Hardy's paradox in phase
space. In the phase-space picture of Hardy's proposed experiment, the
negativity of the predictive Wigner distribution is identified as the culprit
of the disagreement between classical reasoning and quantum mechanics.

26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th