651 research outputs found
Spatial correlations in parametric down-conversion
The transverse spatial effects observed in photon pairs produced by
parametric down-conversion provide a robust and fertile testing ground for
studies of quantum mechanics, non-classical states of light, correlated imaging
and quantum information. Over the last 20 years there has been much progress in
this area, ranging from technical advances and applications such as quantum
imaging to investigations of fundamental aspects of quantum physics such as
complementarity relations, Bell's inequality violation and entanglement. The
field has grown immensely: a quick search shows that there are hundreds of
papers published in this field. The objective of this article is to review the
building blocks and major theoretical and experimental advances in the field,
along with some possible technical applications and connections to other
research areas.Comment: 116 pages, 35 figures. To appear in Physics Report
Experimental Realization of Optimal Noise Estimation for a General Pauli Channel
We present the experimental realization of the optimal estimation protocol
for a Pauli noisy channel. The method is based on the generation of 2-qubit
Bell states and the introduction of quantum noise in a controlled way on one of
the state subsystems. The efficiency of the optimal estimation, achieved by a
Bell measurement, is shown to outperform quantum process tomography
Generation of maximally entangled states of qudits using twin photons
We report an experiment to generate maximally entangled states of
D-dimensional quantum systems, qudits, by using transverse spatial correlations
of two parametric down-converted photons. Apertures with D-slits in the arms of
the twin fotons define the qudit space. By manipulating the pump beam correctly
the twin photons will pass only by symmetrically opposite slits, generating
entangled states between these differents paths. Experimental results for
qudits with D=4 and D=8 are shown. We demonstrate that the generated states are
entangled states.Comment: 04 pages, 04 figure
Multimode Hong-Ou-Mandel interference
We consider multimode two-photon interference at a beam splitter by photons
created by spontaneous parametric down-conversion. The resulting interference
pattern is shown to depend upon the transverse spatial symmetry of the pump
beam. In an experiment, we employ the first-order Hermite-Gaussian modes in
order to show that, by manipulating the pump beam, one can control the
resulting two-photon interference behavior. We expect these results to play an
important role in the engineering of quantum states of light for use in quantum
information processing and quantum imaging.Comment: 4 pages, 6 figures, submitted to PR
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