Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Characterization of conditional state-engineering quantum processes by
  coherent state quantum process tomography   Conditional quantum optical processes enable a wide range of technologies
from generation of highly non-classical states to implementation of quantum
logic operations. The process fidelity that can be achieved in a realistic
implementation depends on a number of system parameters. Here we experimentally
examine Fock-state filtration, a canonical example of a broad class of
conditional quantum operations acting on a single optical field mode. This
operation is based upon interference of the mode to be manipulated with an
auxiliary single-photon state at a beam splitter, resulting in the entanglement
of the two output modes. A conditional projective measurement onto a single
photon at one output mode heralds the success of the process. This operation,
which implements a measurement-induced nonlinearity, is capable of suppressing
particular photon-number probability amplitudes of an arbitrary quantum state.
We employ coherent-state process tomography to determine the precise operation
realized in our experiment. To identify the key sources of experimental
imperfection, we develop a model of the process and identify three main
contributions that significantly hamper its efficacy. The reconstructed tensor
is compared with a model of the process taking into account sources of
experimental imperfection with fidelity better than 0.95. This enables us to
identify three key challenges to overcome in realizing a filter with high
fidelity - namely the single-photon nature of the auxiliary state, high-mode
overlap, and the need for number resolving detection when heralding. The
results show that the filter does indeed exhibit a nonlinear response as a
function of input photon number and preserves the phase relation between Fock
layers of the output state, providing promise for future applications.

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The categories of this paper are: eess
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The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
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The categories of this paper are: comp-gas