5,732 research outputs found
Quantum correlation of light scattered by disordered media
We study theoretically how multiple scattering of light in a disordered
medium can spontaneously generate quantum correlations. In particular we focus
on the case where the input state is Gaussian and characterize the correlations
between two arbitrary output modes. As there is not a single all-inclusive
measure of correlation, we characterise the output correlations with three
measures: intensity fluctuations, entanglement, and quantum discord. We found
that, while a single mode coherent state input can not produce quantum
correlations, any other Gaussian input will produce them in one form or
another. This includes input states that are usually regarded as more classical
than coherent ones, such as thermal states, which will produce a non zero
quantum discord
Superpixel-based spatial amplitude and phase modulation using a digital micromirror device
We present a superpixel method for full spatial phase and amplitude control
of a light beam using a digital micromirror device (DMD) combined with a
spatial filter. We combine square regions of nearby micromirrors into
superpixels by low pass filtering in a Fourier plane of the DMD. At each
superpixel we are able to independently modulate the phase and the amplitude of
light, while retaining a high resolution and the very high speed of a DMD. The
method achieves a measured fidelity for a target field with fully
independent phase and amplitude at a resolution of pixels per
diffraction limited spot. For the LG orbital angular momentum mode the
calculated fidelity is , using DMD pixels. The
superpixel method reduces the errors when compared to the state of the art Lee
holography method for these test fields by and , with a comparable
light efficiency of around . Our control software is publicly available.Comment: 9 pages, 6 figure
Management of the orbital angular momentum of vortex beams in a quadratic nonlinear interaction
Light intensity control of the orbital angular momentum of the fundamental
beam in a quadratic nonlinear process is theoretically and numerically
presented. In particular we analyzed a seeded second harmonic generation
process in presence of orbital angular momentum of the interacting beams due
both to on axis and off axis optical vortices. Examples are proposed and
discussed
Random nonlinear layered structures as sources of photon pairs for quantum-information processing
Random nonlinear layered structures have been found to be a useful source of
photon pairs with perfectly indistinguishable un-entangled photons emitted into
a very narrow spectral range. Localization of the interacting optical fields
typical for random structures gives relatively high photon-pair fluxes.
Superposing photon-pair emission quantum paths at different emission angles,
several kinds of two-photon states (including states with coincident
frequencies) useful in quantum-information processing can easily be generated.Comment: 4 pages, 5 figure
Influence of pump-field scattering to nonclassical-light generation in a photonic band-gap nonlinear planar waveguide
Optical parametric process occurring in a nonlinear planar waveguide can
serve as a source of light with nonclassical properties. Properties of the
generated fields are substantially modified by scattering of the nonlinearly
interacting fields in a photonic band-gap structure inside the waveguide. A
quantum model of linear operator amplitude corrections to amplitude mean-values
provides conditions for an efficient squeezed-light generation as well as
generation of light with sub-Poissonian photon-number statistics. Destructive
influence of phase mismatch of the nonlinear interaction can fully be
compensated using a suitable photonic-band gap structure inside the waveguide.
Also an increase of signal-to-noise ratio of an incident optical field can be
reached in the waveguide.Comment: 10 pages, 12 figure
Conceptos básicos comunicación digital
Comuniación Digital, conceptos básico
Coherence effects in propagation through photonic crystals
We have analytically studied how a partially coherent quasi plane wave is affected by a photonic crystal structure including a grating. The analysis is presented for spatial and temporal cases showing the possibility to determine the coherence characteristics of the pulse.
Transient superdiffusion in correlated diffusive media
This is the author accepted manuscript.Diffusion processes are studied theoretically for the case where the diffusion coefficient is itself a time and position dependent random function. We investigate how inhomogeneities and fluctuations of the diffusion coefficient affect the transport using a perturbative approach, with a special attention to the time scaling of the second moment. We show that correlated disorder can lead to anomalous transport and superdiffusion
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