105 research outputs found
Spherical angular spectrum and the fractional order Fourier transform
International audienceThe notion of a spherical angular spectrum leads to the decomposition of the field amplitude on a spherical emitter into a sum of spherical waves that converge onto the Fourier sphere of the emitter. Unlike the usual angular spectrum, the spherical angular spectrum is propagated as the field amplitude, in a way that can be expressed by a fractional order Fourier transform
A multi-photon Stokes-parameter invariant for entangled states
We consider the Minkowskian norm of the n-photon Stokes tensor, a scalar
invariant under the group realized by the transformations of stochastic local
quantum operations and classical communications (SLOCC). This invariant is
offered as a candidate entanglement measure for n-qubit states and discussed in
relation to measures of quantum state entanglement for certain important
classes of two-qubit and three-qubit systems. This invariant can be directly
estimated via a quantum network, obviating the need to perform laborious
quantum state tomography. We also show that this invariant directly captures
the extent of entanglement purification due to SLOCC filters.Comment: 9 pages, 0 figures, Accepted for publication in Physical Review
Phototraceur UV à micro-miroirs pour la réalisation de fonctions optiques integrées et diffractives
session Me2 " Instrumentation, Caractérisation et Capteurs " [Me2.3]National audienceLe sujet concerne la réalisation d'un phototraceur utilisant un écran à micro-miroirs (DMD : Digital Micro-mirror Device) fonctionnant dans l'UV entre 300 et 400 nm. Ce phototraceur permet la photo-inscription directe dans des polymères de fonctions optiques intégrées et/ou d'éléments diffractifs
Radio Astronomical Polarimetry and the Lorentz Group
In radio astronomy the polarimetric properties of radiation are often
modified during propagation and reception. Effects such as Faraday rotation,
receiver cross-talk, and differential amplification act to change the state of
polarized radiation. A general description of such transformations is useful
for the investigation of these effects and for the interpretation and
calibration of polarimetric observations. Such a description is provided by the
Lorentz group, which is intimately related to the transformation properties of
polarized radiation. In this paper the transformations that commonly arise in
radio astronomy are analyzed in the context of this group. This analysis is
then used to construct a model for the propagation and reception of radio
waves. The implications of this model for radio astronomical polarimetry are
discussed.Comment: 10 pages, accepted for publication in Astrophysical Journa
Jones-matrix Formalism as a Representation of the Lorentz Group
It is shown that the two-by-two Jones-matrix formalism for polarization
optics is a six-parameter two-by-two representation of the Lorentz group. The
attenuation and phase-shift filters are represented respectively by the
three-parameter rotation subgroup and the three-parameter Lorentz group for two
spatial and one time dimensions. It is noted that the Lorentz group has another
three-parameter subgroup which is like the two-dimensional Euclidean group.
Possible optical filters having this Euclidean symmetry are discussed in
detail. It is shown also that the Jones-matrix formalism can be extended to
some of the non-orthogonal polarization coordinate systems within the framework
of the Lorentz-group representation.Comment: RevTeX, 27 pages, no figures, to be published in J. Opt. Soc. Am.
Propagation of transverse intensity correlations of a two-photon state
The propagation of transverse spatial correlations of photon pairs through
arbitrary first-order linear optical systems is studied experimentally and
theoretically using the fractional Fourier transform. Highly-correlated photon
pairs in an EPR-like state are produced by spontaneous parametric
down-conversion and subject to optical fractional Fourier transform systems. It
is shown that the joint detection probability can display either correlation,
anti-correlation, or no correlation, depending on the sum of the orders
and of the transforms of the down-converted photons. We
present analytical results for the propagation of the perfectly correlated EPR
state, and numerical results for the propagation of the two-photon state
produced from parametric down-conversion. We find good agreement between theory
and experiment.Comment: 9 pages, 7 figures, to appear PR
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