Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Accurate polarization preparation and measurement using twisted nematic
  liquid crystals   Generation of particular polarization states of light, encoding information
in polarization degree of freedom, and efficient measurement of unknown
polarization are the key tasks in optical metrology, optical communications,
polarization-sensitive imaging, and photonic information processing. Liquid
crystal devices have proved to be indispensable for these tasks, though their
limited precision and the requirement of a custom design impose a limit of
practical applicability. Here we report fast preparation and detection of
polarization states with unprecedented accuracy using liquid-crystal cells
extracted from common twisted nematic liquid-crystal displays. To verify the
performance of the device we use it to prepare dozens of polarization states
with average fidelity 0.999(1) and average angle deviation 0.5(3) deg. Using
four-projection minimum tomography as well as six-projection Pauli measurement,
we measure polarization states employing the reported device with the average
fidelity of 0.999(1). Polarization measurement data are processed by the
maximum likelihood method to reach a valid estimate of the polarization state.
In addition to the application in classical polarimetry, we also employ the
reported liquid-crystal device for full tomographic characterization of a
three-mode Greenberger--Horne--Zeilinger entangled state produced by a photonic
quantum processor.

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The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
2
The categories of this paper are: math