903 research outputs found
Quantum Erasure by Transverse Indistinguishability
We show that the first experiment with double-slits and twin photons detected
in coincidence can be understood as a quantum eraser. The ``which path''
information is erased by transverse indistinguishability obtained by means of
mode filtering in the twin conjugated beam. A delayed choice quantum eraser
based on the same scheme is proposed.Comment: Submitted for publication in Optics Communication
Image and Coherence Transfer in the Stimulated Down-conversion Process
The intensity transverse profile of the light produced in the process of
stimulated down-conversion is derived. A quantum-mechanical treatment is used.
We show that the angular spectrum of the pump laser can be transferred to the
stimulated down-converted beam, so that images can also be transferred from the
pump to the down-converted beam. We also show that the transfer can occur from
the stimulating beam to the down-converted one. Finally, we study the process
of diffraction through an arbitrarily shaped screen. For the special case of a
double-slit, the interference pattern is explicitly obtained. The visibility
for the spontaneous emitted light is in accordance with the van Cittert -
Zernike theorem for incoherent light, while the visibility for the stimulated
emitted light is unity. The overall visibility is in accordance with previous
experimental results
On The Biphoton Wavelength
We report on an experiment showing that the wavelength of a biphoton is
clearly dependent on the measurement scheme and on the way it is defined. It is
shown that it can take any value, depending on the control of the
interferometer phase differences. It is possible to identify the interference
of the single and two-photon wavepackets as particular cases of the most
general interference process. The variable wavelength has no implication on the
energy of the individual photons neither on the total energy of the biphoton
Image formation by manipulation of the entangled angular spectrum
We demonstrate theoretical and experimentally how it is possible to
manipulate an entangled angular spectrum of twin beams, in order to reconstruct
correlated images with coincidence detection. The entangled angular spectrum
comes from the pump and the image is obtained only if signal and idler are
properly treated.Comment: Submitted for publication in Optics Communication
Quantum Distillation Of Position Entanglement With The Polarization Degrees Of Freedom
Sources of entangled photon pairs using two parametric down-converters are
capable of generating interchangeable entanglement in two different degrees of
freedom. The connection between these two degrees of freedom allows the control
of the entanglement properties of one, by acting on the other degree of
freedom. We demonstrate experimentally, the quantum distillation of the
position entanglement using polarization analyzers.Comment: Submitted for publication in Optics Communication
Scaling Function, Universality and Analytical Solutions of Generalized One-Species Population Dynamics Models
We consider several one-species population dynamics model with finite and
infinite carrying capacity, time dependent growth and effort rates and solve
them analytically. We show that defining suitable scaling functions for a given
time, one is able to demonstrate that their ratio with respect to its initial
value is universal. This ratio is independent from the initial condition and
from the model parameters. Although the effort rate does not break the model
universality it produces a transition between the species extinction and
survival. A general formula is furnished to obtain the scaling functions.Comment: 8 pages and 4 figure
Control of conditional pattern with polarization entanglement
Conditional interference patterns can be obtained with twin photons from
spontaneous parametric down-conversion and the phase of the pattern can be
controlled by the relative transverse position of the signal and idler
detectors. Using a configuration that produces entangled photons in both
polarization and transverse momentum we report on the control of the
conditional patterns by acting on the polarization degree of freedom.Comment: Submitted for publication in Optics Communication
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